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

Annotations only supply readOnlyHint=false; the description carries the rest and does so richly: it discloses that chunk and deposit reversals happen in the ledger only (not real funds), that a refundable deposit is involved, and that a goal.cancelled event is emitted. That is exactly the side-effect disclosure an agent needs before mutating state.

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?

One sentence, front-loaded with the action, the resource, and the endpoint before the parenthetical side-effect detail. No filler or redundancy.

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?

For a single-parameter mutation with no output schema, the definition covers action, route, and consequences well. It stops short of describing the response body or failure modes (e.g., cancelling an already-cancelled goal), which would close the remaining gap.

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?

There is a single parameter with 100% schema description coverage, and the schema already states the goalId comes from create_test_goal. The description only echoes :goalId as a path segment, adding no new semantics, so the baseline of 3 applies.

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?

Names a specific verb (cancels) and resource (sandbox goal), plus the exact HTTP route POST /goals/:goalId/cancel. It is immediately distinguishable from siblings like create_test_goal, get_goal, and simulate_goal_event.

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 phrase 'as the user's server would when a customer cancels' tells the agent this is a simulation of a real cancellation flow, which is clear context for choosing it. It doesn't explicitly name when to use simulate_goal_event versus this tool, or state prerequisites such as the goal needing to exist in an uncancelled state.

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