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

Annotations already cover readOnly/idempotent/non-destructive/closed-world, so the bar is lower, and the description still adds meaningful context: the key value is masked and never returned in clear text, and Admin permission is required. It could note pagination limits or result counts, but the security and permission disclosures are the high-value items.

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-loads scope and ordering before constraints, and every clause carries information (fields, security caveat, permission, slug rule). The phrase 'Mirrors API keys' is slightly opaque, keeping it just short of ideal.

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?

There is no output schema, so the description compensates by enumerating returned fields (id, name, masked value, created by, created, last used) and the masked-value caveat. Permission requirements and the slug rule complete what an agent needs to invoke it correctly.

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% and the single 'project' slug parameter is fully documented there. The description restates the same omit-for-single-project rule without adding syntax or format detail beyond the schema, 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 (list) and resource (a project's live API keys), plus scope and ordering ('newest first'). It is trivially distinguishable from create_api_key and revoke_api_key among the siblings.

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?

Gives clear operational context: it 'needs project Admin' and explains when to pass the slug versus omitting it (organization with a single live project). It does not explicitly name alternatives, but the create/revoke siblings make the boundary self-evident.

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