Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=false, destructiveHint=false and idempotentHint=false, so the safety profile is covered. The description adds one genuine behavioral fact beyond annotations — that mocks expire — but never says how long they live, whether name must be unique, or how creation interacts with existing mocks. Useful but thin for a mutation tool with nested config.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, no filler, and the core action is front-loaded before the mode-specific detail. Every clause carries information an agent needs.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

This is a complex tool with 7 parameters, nested objects, and no output schema, yet the description covers only the HTTP-route and WebSocket shapes. The llm test double, crud mock, visibility and expiration timing — all present in the schema — go unmentioned, so an agent must read the schema to understand most of the tool's surface.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 43%, so the schema only partly documents the 7 parameters. The description compensates for the websocket branch by naming echo, welcome messages and exact text replies, and it explains the routes=[] coupling. It says nothing about the llm, crud, visibility or name parameters, leaving several significant gaps unfilled.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb and resource: "Create an expiring HTTP or WebSocket mock." It also states the two modes (HTTP routes vs WebSocket), which lets an agent distinguish it from sibling call_mock_api, inspect_mock_api and delete_mock_api. It does not explicitly name those siblings, so it stops short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The second sentence gives concrete mode-selection guidance: set routes to [] and configure echo/welcome/replies in websocket for WebSocket mocks. That is real how-to guidance for one branch, but there is no guidance on when to use create_mock_api versus call_mock_api or inspect_mock_api, and no mention of prerequisites or the lifetime of an "expiring" mock.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.