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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds genuinely new behavioral facts: keys are truncated so no usable secret is ever returned, and revoked keys remain in the listing with dates. Those are exactly the security and result-shape details an agent cannot infer from the annotation block.

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?

Front-loaded with the payload (what each record contains), followed by two short constraint sentences. The 'fact worth having before revoking one' clause is the only flourish, and it carries real decision value rather than filler.

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 no output schema, the description must explain the return shape and does so field by field, plus the important caveat that revoked keys appear in the results. Nothing an agent needs in order to call this and interpret the output 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?

The tool takes zero parameters, so there is nothing to disambiguate and the baseline is 4. The description correctly implies a full-account listing with no filters, matching 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?

States a specific verb and resource ('List the API keys on this account') and immediately enumerates what is returned: name, partial key characters, creation date, last-used date. It is clearly distinguishable from the mutating sibling revoke_api_key, which the description implicitly contrasts by framing the listing as the step 'before revoking one.'

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?

Supplies clear usage context: consult it before revoking a key, and use it to tell a revoked key (present with a date) from a key that never existed. It stops short of naming revoke_api_key as the alternative or stating exclusions, so it gets a 4 rather than a 5.

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