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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds the underlying REST mapping (GET /v2/usercollection/{collection}/{document_id}), which clarifies the path structure, but discloses nothing about error behavior for invalid ids, missing documents, or the sandbox flag's effect.

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, zero filler, with the core action stated first and the id-prerequisite and endpoint mapping following. Every sentence earns its place.

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 read-only single-resource fetch with no output schema, the description plus annotations and full schema coverage give an agent enough to invoke it correctly. It could optionally note the sandbox alternative or empty-result behavior, but nothing essential is missing.

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%, so the schema already documents collection, document_id, and sandbox (including the enum's 16 values). The description only restates that the id belongs to one collection and implies the path template; it adds no new syntax or format detail, so baseline 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?

States a specific verb and resource ('Fetch a single document by id from one collection') and explicitly distinguishes itself from the sibling oura_list_documents by naming it as the id source. An agent can separate this single-fetch tool from the list tool without opening either schema.

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?

Explicitly tells the agent where the required id comes from ('Ids come from oura_list_documents'), which is the key prerequisite for calling this tool. It stops short of stating when-not to use it (e.g., bulk retrieval), so it is strong context without full routing guidance.

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