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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, so the safety profile is covered. The description adds valuable context by specifying that the response includes the learner's answers keyed by block id, which is beyond what annotations provide. It does not contradict annotations and gives useful detail about the return content.

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, concise sentence that front-loads the action and resource. It contains no extraneous words and every phrase adds value, clearly stating what is fetched and what it includes.

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 get-by-id tool with an output schema, the description is complete. It tells the agent exactly what is returned (the learner run including answers keyed by block id) and the only required parameter is documented in the schema. There are no missing details that would prevent correct invocation.

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 100% because the sole parameter 'id' has a description already stating it is the completion id from list_completions. The tool description does not add any additional parameter semantics 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 clearly states the tool fetches one learner run (completion) by id, and specifies that it includes the answers keyed by block id. This is a specific verb and resource, and it distinguishes from siblings like list_completions (which lists) and get_generation (which gets generation status). The purpose is 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 you have a specific completion id, and the parameter description references list_completions as the source of ids, providing clear context. However, it does not explicitly state when to use this tool over alternatives or mention any exclusions, so guidance is implied rather than explicit.

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