feat(agent-tool-set)

[mattapperson]

Summary

• Adds @openrouter/agent-tool-set — a new workspace package for the SDK's tool() / callModel APIs.
• Adds a new activeTools?: readonly string[] option to callModel so inferTools() output can be spread directly into a request, with filtering applied before both API conversion and executor registration.
• Predicates receive { state: ConversationState, context: TShared }. InferToolSet<T> is mapped to this SDK's streaming event shapes (ToolPreliminaryResultEvent / ToolResultEvent).

Public API (@openrouter/agent-tool-set)

• createToolSet({ tools, mutable? }) — array input; duplicate names throw at construction. ServerToolBase entries are accepted and skipped (client-tool-only activation).
• .tools getter (full, ordered).
• .activate / .deactivate — string or array of names.
• .activateWhen / .deactivateWhen — name+predicate or { name: predicate, ... } bulk form. Last-call-wins per tool.
• .inferTools(input?) → { tools: Tool[]; activeTools: string[] }.
• .clone({ mutable? }).
• Types: ActivationInput, ActivationPredicate, InferToolSet.

Agent changes

• BaseCallModelInput gains activeTools?: readonly string[]; clientOnlyFields includes it.
• callModel filters tools by activeTools (Set membership) before convertToolsToAPIFormat and before passing to ModelResult, so filtered tools are neither advertised to the model nor callable by the executor. Server tools bypass the filter (they have no name to match against).

Test plan

• pnpm build — both packages compile
• pnpm typecheck — strict mode clean
• pnpm test — 268 unit tests pass (249 agent + 19 agent-tool-set)
  • packages/agent-tool-set/tests/unit/tool-set.test.ts — 19 cases covering construction, duplicate-name error, activate/deactivate (string + array), activateWhen/deactivateWhen (single + bulk), last-call-wins, immutable vs mutable, clone, input handling, and predicate typing
  • packages/agent/tests/unit/call-model-active-tools.test.ts — 3 cases verifying the outbound request body via a capturing HTTPClient
• pnpm lint — Biome clean
• pnpm changeset status — both packages bumped minor

Release

.changeset/agent-tool-set.md — minor bump for both @openrouter/agent-tool-set (0.1.0 initial) and @openrouter/agent (new activeTools option).

[robert-j-y]

needs a rebase onto the current turborepo-migration — PR #30 landed and widened Tool to ClientTool | ServerToolBase. After rebase, two sites break:

1. packages/agent/src/inner-loop/call-model.ts:102 — produces TS2339: Property 'function' does not exist on type 'Tool'. Property 'function' does not exist on type 'ServerToolBase'. at compile time, and TypeError: Cannot read properties of undefined (reading 'name') at runtime if any serverTool(...) is in the array. Change:

const filteredTools = activeSet ? tools?.filter((t) => activeSet.has(t.function.name)) : tools;

to:

const filteredTools = activeSet
  ? tools?.filter((t) => isServerTool(t) || activeSet.has(t.function.name))
  : tools;

(import isServerTool from ../lib/tool-types.js)

2. packages/agent-tool-set/src/tool-set.ts buildToolsMap (lines 32–42) — same root cause. Compile error doesn't surface yet only because agent-tool-set resolves @openrouter/agent through the stale compiled .d.ts; runtime t.function.name still throws on any server tool passed to createToolSet. Change:

for (const t of tools) {
  const name = t.function.name;
  if (map.has(name)) throw new Error(`Duplicate tool name: "${name}"`);
  map.set(name, t);
}

to:

for (const t of tools) {
  if (isServerTool(t)) continue;
  const name = t.function.name;
  if (map.has(name)) throw new Error(`Duplicate tool name: "${name}"`);
  map.set(name, t);
}

(import isServerTool from @openrouter/agent)

Server tools have no name to activate by, so skipping them keeps ToolSet client-tool-only while still allowing users to pass a mixed array through.

3. PR description: InferActiveTools and InferInactiveTools are listed under "Types:" but are not exported from packages/agent-tool-set/src/index.ts. Remove or add.

[mattapperson]

Two concerns on the new ToolSet surface worth a look before merge.

[mattapperson]

reviewed, no issues found