Interface: DeferToolsOptions

Defined in: deferTools.ts:13

How registerTools defers tools behind search / describe / call.

Properties

except?

optional except?: (args) => boolean

Defined in: deferTools.ts:22

Tools that are not deferred: they are also registered as standalone MCP tools, and stay reachable through search / describe / call too.

Defaults to the tools linked to an MCP Apps view: a host finds a tool's view through that tool's own tools/list entry, so a view behind call would never render.

Parameters

Parameter	Type
args	{ tool: Tool; }
args.tool	Tool

Returns

boolean

---

names?

optional names?: object

Defined in: deferTools.ts:28

The names of the three tools that reach the deferred ones, to avoid a collision with a standalone tool or to defer two sets on one server.

call?

optional call?: string

describe?

optional describe?: string

search?

optional search?: string

Default

{ search: 'search', describe: 'describe', call: 'call' }

---

schemaOnError?

optional schemaOnError?: "always" | "invalidArguments"

Defined in: deferTools.ts:59

Which failed calls carry the tool's input schema.

• 'invalidArguments' — only arguments that fail the tool's schema, so a call made without describe corrects itself in one retry. A tool's own error result or a thrown error is usually a refusal of the operation (a 404, a 409), and a large schema on every refusal costs more context than deferring saved.
• 'always' — those carry it too. For tools that do not validate their arguments, whose errors may be argument errors only the API detects.

Default

'invalidArguments'

---

search?

optional search?: (args) => Tool[] | Promise<Tool[]>

Defined in: deferTools.ts:34

Replaces the default ranking, e.g. with embeddings. Receives only the tools visible lets through; the result is cut to limit. rankTools is the default, for a fallback.

Parameters

Parameter	Type
args	ToolSearchArgs

Returns

Tool[] | Promise<Tool[]>

---

searchLimit?

optional searchLimit?: number

Defined in: deferTools.ts:39

How many tools search returns when the model does not say.

Default

10

---

searchMaxLimit?

optional searchMaxLimit?: number

Defined in: deferTools.ts:45

The largest limit search accepts. With no ceiling, an empty query lists every tool, more than a client's context holds.

Default

50, or searchLimit when that is higher

---

visible?

optional visible?: (args) => boolean

Defined in: deferTools.ts:70

Runs on every search, describe and call. A tool it rejects is absent from all three; call answers it as an unknown name. Tools except keeps standalone are listed on tools/list regardless.

Parameters

Parameter	Type
args	{ tool: Tool; }
args.tool	Tool

Returns

boolean

Example

visible: ({ tool }) => canUse({ identity: getIdentity(), tool: tool.name }),