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

Annotations already provide readOnlyHint=true, so the safe read behavior is known. The description adds useful context about the fields returned (capabilities, expiry, usage) and the REST endpoint, but does not go beyond that to include response format or error conditions, which is acceptable for a simple read tool.

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 two sentences, front-loaded with the core action, and includes the REST endpoint for reference. Every word earns its place; no filler or repetition.

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 tool with one required parameter and no output schema, the description adequately covers the purpose, input, and data scope. It lacks detail about the return structure, but no output schema exists and the tool is simple enough that the description is sufficient for 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 coverage is 100% with the keyId parameter described as 'The key id.' The description does not add meaning beyond the schema, but the schema already fully documents the only parameter, so the baseline of 3 is appropriate.

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 'Get details of a single auth key / API access token by id (capabilities, expiry, usage)', providing a specific verb, resource, and scope. It distinguishes this from sibling tools like list_keys (enumerating keys) and delete_key.

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 phrase 'single ... by id' gives clear context that this is for retrieving one specific key when you already have its ID. It does not explicitly mention alternatives like list_keys, but the usage is clear from the wording.

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