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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is fully covered before the description is read. The description's contribution is the field list returned and the connection-test use case, but it says nothing about failure behavior when the key is invalid, which is the natural concern for a connectivity probe.

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?

Two sentences, no filler, with the core action and returned fields stated first and the connection-test hint appended. Every clause carries information an agent can act on.

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?

With a rich output schema, four annotations, and no parameters, almost nothing is left for the description to carry, and it covers purpose, returned identity fields, and one practical use. Only the absence of any error/credential-failure note keeps it from being fully complete for a connection-test tool.

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 takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The parenthetical field names describe the response, not inputs, and do not conflict with 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 names a specific verb and resource ("Fetch the account and team behind the API key") and enumerates the identifying fields returned (apiKeyId, apiKeyNickname, email, displayName, teamId). No sibling tool (get_billing_account, get_entity, get_project) retrieves the credential's own account, so an agent can distinguish it immediately.

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?

"Use it as a connection test" gives a concrete triggering context for the tool, which is the main ambiguous case for a get-me endpoint. It stops short of stating when not to use it or naming alternatives, but there is no competing tool that overlaps this capability.

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