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

Annotations declare a non-read-only, non-idempotent write, and the description adds real context beyond them: the call is free, the key must own the recommendation_id, and the data feeds this key's private history rather than a public leaderboard. It does not address what happens on duplicate submissions, which matters given idempotentHint=false.

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?

Three short sentences, front-loaded with the cost signal ('Free.') that an agent would want before deciding to call. No redundant restatement of the schema.

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?

With no output schema, the description still conveys sequencing, ownership scoping, cost, and downstream effect on ranking. The main omission is duplicate/retry behavior for a non-idempotent write, which the annotations alone flag but do not explain.

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 coverage is 100% and every parameter is documented in the schema itself. The description echoes success, latency_ms, and cost_usd without adding format or validation meaning beyond that, 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?

The description states a specific action (report success, latency_ms, and cost_usd after a pick) and frames it as the counterpart to ranking, which distinguishes it from rank_tools_for_task. It stops short of a single crisp verb+resource sentence, relying on 'report' and 'the pick' rather than naming the resource outright.

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?

'After you call the pick' gives an explicit trigger condition and ordering relative to the sibling rank tool. The constraint that only a recommendation_id issued to this API key is accepted adds a clear precondition, though no explicit 'when not to use' case is stated.

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