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

Annotations already declare read-only and idempotent behavior, which the description doesn't need to repeat. The description adds the selection behavior by name, id, or random, including the 'random' retrieval mode which is a meaningful behavioral detail. It does not describe return format, but annotations lower the bar.

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 description is a single, front-loaded sentence that communicates the core functionality without wasted words. It is perfectly sized.

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 simple read-only fetch, the description covers the basic operation, but it omits important usage details such as parameter exclusivity, behavior when no parameters are provided, and what the response contains. Since there is no output schema, the description needs to give a bit more context, making it incomplete for an AI agent to invoke correctly in all scenarios.

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?

With 0% schema description coverage, the description is the sole source of parameter meaning. It explains that name, id, and random are the lookup criteria for fetching an exercise, adding meaning beyond the raw parameter names. However, it leaves ambiguity about mutual exclusivity and the behavior when multiple parameters are provided, preventing a higher score.

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 uses the specific verb 'Fetch' with resource 'one exercise' and specifies three retrieval modes (name, id, random). This clearly distinguishes from search_exercises that would return multiple results. It is concise and unambiguous.

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 usage when retrieving a single exercise by identifier or randomly, but it does not explicitly state when not to use it or mention alternatives like search_exercises or resolve_exercise. With siblings present, the lack of explicit exclusion could lead to tool mis-selection.

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