Who am I?

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

Annotations already declare readOnlyHint=true. Description adds behavioral details about auth_type behavior (api_key vs oauth), and returns subscription, budget, rate-limit. No contradictions. Goes beyond annotation by explaining when key is null.

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?

Description is concise with front-loaded main purpose, followed by useful details on auth types, chaining recommendation, and error handling. Every sentence adds value with no fluff.

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?

Given zero parameters, readOnlyHint annotation, and available output schema, the description covers all necessary information: what it does, when to call, auth differentiation, errors. Fully complete for a simple identity 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?

No parameters, so baseline 4 applies. The schema has 0 parameters and 100% coverage, so description doesn't need to add param info. It correctly omits any parameter discussion as there are none.

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 it wraps 'GET /me' and returns workspace identity, subscription, competitor budget, and rate-limit snapshot. It distinguishes from sibling tools like list_competitors, get_competitor, etc., which have different purposes.

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 says 'Call first in a session to verify auth and workspace identity before any other tool,' providing clear when-to-use guidance. Also explains error handling for unauthorized and rate-limited responses.

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