openclaw/docs/tools/tool-search.md

summary, title, read_when

summary	title	read_when
Tool Search: compact large OpenClaw tool catalogs behind search, describe, and call	Tool Search	You want OpenClaw agents to use a large tool catalog without adding every tool schema to the prompt You want OpenClaw tools, MCP tools, and client tools exposed through one compact runtime surface You are implementing or debugging tool discovery for OpenClaw runs

Tool Search is an experimental OpenClaw agent runtime feature. It gives agents one compact way to discover and call large tool catalogs. It is useful when the run has many available tools but the model is likely to need only a few of them.

This page documents OpenClaw Tool Search. It is not the Codex-native tool search or dynamic-tools surface. Codex-native code mode, tool search, deferred dynamic tools, and nested tool calls are stable Codex harness surfaces and do not depend on tools.toolSearch.

For the generic OpenClaw runtime that exposes a QuickJS-WASI exec/wait surface instead of Tool Search controls, see Code Mode.

When enabled for OpenClaw runs, the model automatically receives a bounded directory of the available trusted tool names and descriptions. By default, it also receives one tool_search_code tool, plus any direct-only tools whose structured results cannot cross the compact bridge. The code tool runs a short JavaScript body in an isolated Node subprocess with an openclaw.tools bridge:

const hits = await openclaw.tools.search("create a GitHub issue");
const tool = await openclaw.tools.describe(hits[0].id);
return await openclaw.tools.call(tool.id, {
  title: "Crash on startup",
  body: "Steps to reproduce...",
});

The catalog can include catalog-eligible OpenClaw tools, plugin tools, MCP tools, and client-provided tools. The directory gives the model an idea of which trusted capabilities it can discover without exposing every cataloged schema up front. It also explains that policy-approved MCP and client tools may be discoverable. Their untrusted names and descriptions are not copied into the system prompt. Instead, the model searches compact descriptors, describes one selected tool when it needs the exact schema, and calls that tool through OpenClaw. Direct-only tools remain model-visible and are not added to the catalog.

Codex harness runs do not receive these experimental OpenClaw Tool Search controls. OpenClaw passes product capabilities to Codex as dynamic tools, and Codex owns the stable native code mode, native tool search, deferred dynamic tools, and nested tool calls.

How a turn runs

At planning time the OpenClaw embedded runner builds the effective catalog for the run:

1. Resolve the active tool policy for the agent, profile, sandbox, and session.
2. List eligible OpenClaw and plugin tools.
3. List eligible MCP tools through the session MCP runtime.
4. Add eligible client tools supplied for the current run.
5. Keep core coding primitives and direct-only tools model-visible and index compact descriptors for the remaining catalog-eligible tools.
6. Add a deterministic, bounded, policy-filtered capability directory to the cache-stable system-prompt prefix.
7. Expose the OpenClaw code bridge, the structured fallback tools, or the compact directory surface alongside those stable, directly callable tools.

At execution time every real tool call returns to OpenClaw. The isolated Node runtime does not hold plugin implementations, MCP client objects, or secrets. openclaw.tools.call(...) crosses the bridge back into the Gateway, where the normal policy, approval, hook, logging, and result handling still apply.

Modes

tools.toolSearch has three model-facing modes:

• code: exposes tool_search_code, the default compact JavaScript bridge, alongside the capability directory and direct-only tools.
• tools: exposes tool_search, tool_describe, and tool_call as plain structured tools for providers that should not receive code, alongside the capability directory and direct-only tools.
• directory: exposes tool_search, tool_describe, and tool_call plus a bounded, cache-stable prompt directory. Core coding primitives, direct-only tools, and tools required by the run's delivery policy remain visible; other schemas stay deferred.

All modes use the same policy-filtered catalog and normal OpenClaw execution path. Tools marked catalogMode: "direct-only" stay outside that catalog and remain model-visible. If the current runtime cannot launch the isolated Node code-mode child process, the default code mode falls back to tools before catalog compaction. In directory mode, client-provided tools stay directly visible for the current run while OpenClaw tools, plugin tools, and MCP tools can be compacted behind the directory catalog. A direct call to an exact hidden directory name is hydrated from that same authorized catalog before execution.

All modes are experimental. Prefer direct tool exposure for small OpenClaw tool catalogs, and prefer the Codex-native stable surfaces for Codex harness runs.

There is no separate source-selection config. When Tool Search is enabled, the catalog includes catalog-eligible OpenClaw, MCP, and client tools after normal policy filtering; direct-only tools are retained separately.

Why this exists

Large catalogs are useful but expensive. Sending every tool schema to the model makes the request larger, slows planning, and increases accidental tool selection.

Tool Search changes the shape:

• direct tools: the model sees every selected schema before the first token
• Tool Search code mode: the model sees one compact code tool, a bounded capability directory, a short API contract, and any direct-only tools
• Tool Search tools mode: the model sees three compact structured fallback tools, the same capability directory, and any direct-only tools
• Tool Search directory mode: the model sees a bounded directory plus search/describe/call controls, policy-required direct tools, and any direct-only tools
• during the turn: the model can load remaining schemas as needed

Direct tool exposure is still the right default for small catalogs. Tool Search is best when one run can see many tools, especially from MCP servers or client-provided app tools.

The capability directory is sorted by tool name, limited to 18,000 characters, and built from the already policy-filtered catalog. OpenClaw reuses the rendered directory for an unchanged catalog snapshot and places it above the system-prompt cache boundary. User messages, per-turn tool guesses, session identifiers, and untrusted MCP or client metadata do not enter the directory. This keeps repeated turns eligible for prompt KV-cache reuse. When the authorized catalog changes, OpenClaw builds a new directory for the new snapshot.

API

openclaw.tools.search(query, options?)

Searches the effective catalog for the current run.

Queries must be written in English. Ranking is lexical (Okapi BM25 over tool names, descriptions, and first-party parameter names and descriptions), with light English stemming so scheduling reaches a tool described as Schedule a recurring task, and a small intent expansion so look up the price reaches one described as Search the web. Tool names and descriptions are written in English, so a query in another language will usually match nothing. It is not rejected — a catalog may legitimately describe a tool in another script — but it is also no longer answered with an arbitrary slice of the catalog presented as if it were ranked, which is what the previous scorer did whenever a query produced no usable terms. Both tool_search and the code-mode bridge state this requirement in their model-facing descriptions.

Untrusted parameter schemas are never indexed. MCP and client tools are matched on name and description only, which is the same boundary that defers their input signatures as input: "unknown".

Results are compact and safe to put back into prompt context. Each hit includes a bounded TypeScript-style input signature, such as { id: string; mode?: "drip" | "flood" }, so the model can skip describe when that signature is sufficient. A trusted OpenClaw core or plugin tool may also include a compact output hint, such as Array<{ id: string; paid: boolean }>. MCP and client output-schema claims are not promoted into this trusted hint. Their untrusted input schemas are also deferred as input: "unknown"; use describe before calling them. Open, oversized, or otherwise partial output schemas omit the hint and remain available through describe instead.

const hits = await openclaw.tools.search("calendar event", { limit: 5 });

openclaw.tools.describe(id)

Loads full metadata for one search result, including the exact input schema and the trusted full outputSchema when the tool declares one.

const calendarCreate = await openclaw.tools.describe("mcp:calendar:create_event");

openclaw.tools.call(id, args)

Calls a selected tool through OpenClaw and returns the raw { tool, result } envelope. JSON-returning tools normally place their value in result.details. OpenClaw validates a trusted core or plugin tool's declared input schema before execution. Missing required arguments, incorrect types, and forbidden properties return actionable tool errors instead of executing the tool; misspelled properties include a suggested parameter when available. If a trusted tool also declares outputSchema, OpenClaw compiles that schema before execution and validates final details after normal tool hooks before returning the catalog call. MCP and client-owned schemas remain deferred to their owning execution boundary.

In structured mode, tool_call also repairs flattened target arguments from local models. It preserves target fields such as id and name, and rejects ambiguous tool selectors instead of calling the wrong tool. Nest target arguments under args when a target field matches another cataloged tool.

await openclaw.tools.call(calendarCreate.id, {
  summary: "Planning",
  start: "2026-05-09T14:00:00Z",
});

Tool authors declare output contracts on the tool's outputSchema property. It describes AgentToolResult.details, not rendered content blocks. Include all non-throwing variants or omit it for unstable results. See Code Mode output contracts and Tool plugins.

The structured fallback mode exposes the same operations as tools:

• tool_search
• tool_describe
• tool_call

Directory mode exposes:

• tool_search
• tool_describe
• tool_call

It also keeps core file and shell primitives, client-provided tools, direct-only tools, and policy-required delivery tools directly visible. Other authorized tool schemas stay deferred rather than changing with each user prompt. MCP tools cannot impersonate a directly visible core or policy-required delivery tool. If the bounded directory omits entries, use tool_search to find them and tool_describe to retrieve their full schemas. If the model requests an exact hidden directory tool name directly, OpenClaw resolves it from the authorized catalog before normal execution. Directory-mode client tool names must not collide with OpenClaw, plugin, or MCP tool names because exact deferred dispatch uses those names.

Runtime boundary

The code bridge runs in a short-lived Node subprocess. The subprocess starts with Node permission mode enabled, an empty environment, no filesystem or network grants, and no child-process or worker grants. OpenClaw enforces a parent-process wall-clock timeout and kills the subprocess on timeout, including after async continuations.

The runtime exposes only:

• console.log, console.warn, and console.error
• openclaw.tools.search
• openclaw.tools.describe
• openclaw.tools.call

Normal OpenClaw behavior still applies to final calls:

• tool allow and deny policies
• per-agent and per-sandbox tool restrictions
• channel/runtime tool policy
• approval hooks
• plugin before_tool_call hooks
• session identity, logs, and telemetry

Config

Enable Tool Search for OpenClaw runs with the default code bridge:

openclaw config set tools.toolSearch true

Equivalent JSON:

{
  tools: {
    toolSearch: true,
  },
}

Use the structured fallback tools instead for OpenClaw runs:

{
  tools: {
    toolSearch: {
      mode: "tools",
    },
  },
}

Use the compact directory surface instead for OpenClaw runs:

{
  tools: {
    toolSearch: {
      mode: "directory",
    },
  },
}

Tune code-mode timeout and search result limits (values shown are the defaults):

{
  tools: {
    toolSearch: {
      mode: "code",
      codeTimeoutMs: 10000,
      searchDefaultLimit: 8,
      maxSearchLimit: 20,
    },
  },
}

The runtime clamps codeTimeoutMs to 1000-60000, maxSearchLimit to 1-50, and searchDefaultLimit to 1..maxSearchLimit.

Disable it:

{
  tools: {
    toolSearch: false,
  },
}

Prompt and telemetry

Code mode attaches a telemetry object to every tool_search_code result:

• catalogSize: number of catalog entries the runtime resolved
• sources: catalog entry counts split into openclaw, mcp, and client
• searchCount, describeCount, callCount: running totals for the catalog session, carried across calls rather than reset per call

tools and directory mode emit no telemetry object; their tool_search, tool_describe, and tool_call results carry only the catalog data for that operation. OpenClaw does not record serialized tool or prompt byte counts. The E2E scenario measures provider payload bytes separately from the mock provider lane, not from the runtime.

Regardless of mode, target tool calls are projected into the session transcript as normal tool call and tool result pairs, and search, describe, and call results carry each tool's id and source. Session logs therefore still answer:

• how many tool schemas the model saw up front
• how many search and describe operations it performed
• which final tool was called
• whether the result came from OpenClaw, MCP, or a client tool

E2E validation

The QA Lab gateway scenario proves both paths with the OpenClaw runtime:

pnpm openclaw qa suite --provider-mode mock-openai --scenario tool-search-gateway-e2e

It creates a temporary fake plugin with a large tool catalog, starts the mock OpenAI provider, starts a Gateway once in direct mode and once with Tool Search enabled, then compares provider request payloads and session logs.

The regression proves:

1. Direct mode can call the fake plugin tool.
2. Tool Search can call the same fake plugin tool.
3. Direct mode exposes the fake plugin tool schemas directly to the provider.
4. Tool Search exposes only the compact bridge plus any direct-only tools.
5. The Tool Search request payload is smaller for the large fake catalog.
6. Session logs show the expected tool-call counts and bridged call telemetry.

Failure behavior

Tool Search should fail closed:

• if a tool is not in the effective policy, search should not return it
• if a selected tool becomes unavailable, tool_call should fail
• if policy or approval blocks execution, the call result should report that block instead of bypassing it
• if the code bridge cannot create an isolated runtime, use mode: "tools" or disable Tool Search for that deployment

Related

• Tools and plugins
• Multi-agent sandbox and tools
• Exec tool
• ACP agents setup
• Building plugins