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

Annotations already declare readOnlyHint=true and destructiveHint=false, which cover the safety profile. The description adds that it is free and a closed value set, consistent with openWorldHint=false. It also mentions a feedback channel, but that is tangential to the tool's core behavior. The description does not contradict annotations and provides minimal extra behavioral context beyond what annotations already offer.

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?

The main purpose is front-loaded in the first sentence. The description is about three sentences long, but includes a lengthy aside about the feedback endpoint and a philosophical note on 'paywall on discovery.' While informative, this extra content is not essential to the tool's operation and makes it slightly less concise than it could be.

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?

Given the tool is simple (no params, no output schema) and annotations cover safety, the description sufficiently conveys the core purpose and the data returned ('what we hold for each'). It is not explicit about the response format (e.g., list, map, field names), but for a discovery endpoint with zero parameters, the description provides enough for an agent to use it correctly.

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?

The tool has zero parameters, and the schema is an empty object. With no parameters to document, the baseline is 4. The description does not need to elaborate on parameters; instead, it focuses on the output, which is appropriate. It explains that the tool returns the set of venue ids and associated holdings, adding meaning beyond the empty schema.

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 clearly states the tool lists 'every venue id drift_check can be aimed at, with what we hold for each.' This is a specific verb (list/discover), a clear resource (venue ids for drift_check), and it differentiates itself from siblings like drift_check (the operation) and drift_baseline. The phrase 'closed value set' also distinguishes it as a discovery endpoint.

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 description implies this tool is a prerequisite for calling drift_check: without it, a caller cannot name a valid venue id. It states that otherwise 'a caller can honour the input schema and still never name something buyable,' which clearly signals the usage context. It doesn't explicitly name alternatives or exclusions, but the purpose is clear enough for an agent to infer when to use it.

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