Corey James- ~42,000tokens of tool schema an agent had carried every turn
- 24meeting tools, each with a minimal exact schema
- 520characters in the discovery tool's description, held there by a test
Tools shaped like jobs, not endpoints
FAFOHive: when I added in-house social integrations to the tool hub, the fast path was to generate one tool per vendor endpoint. I took it once. The X module's first build compiled its tools straight from the vendor's OpenAPI specification. They were cheap to make, expensive to call and easy for an agent to misuse. I withdrew that surface and replaced it with tools shaped like the jobs agents actually do, trading generated breadth for designed workflow tools with costs and guards.
A written standard every tool must meet
I wrote the standard every tool in the estate has to meet, and its rulings. Its first rule is that a tool is a job. Errors come back verbatim, and an empty result never stands in for a failure.
A write that cannot be read back comes back marked as not confirmed. Every create ships with its delete.
its purpose, when something cheaper fits, the exact cost formula, the batch alternative, cache behaviour, pagination cost, side effects, the return shape and its errors.
Cost and repeats an agent can reason about
The X tools state their cost in units and refuse work once the monthly budget is spent.
An agent cannot budget what it cannot see, so every call states its cost.
Spent: the next call is refused before it reaches the platform.
A lifecycle test through the agent tools alone
The Facebook module proved the standard against a real platform, with nothing allowed to reach it except through a tool.
The governed gateway these tools sit behind is in Agents with real tools and no keys.
Meeting tools a model cannot misuse
Helix: the meeting action server lets any model act in a Teams meeting as one employee. I wanted a model to be unable to send a malformed or ambiguous command.
additionalProperties: false, exact required fields, declared side effects and sensitivity, no model-facing action enums.See A meeting attendee that will not fake it.
One discovery tool instead of a catalog
Capabilities model: here the design problem was the size of the tool surface itself. The whole schema on every turn became one discovery tool, whose description length is enforced by a test.