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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so safety is covered structurally. The description adds genuinely useful behavioral context beyond that: it discloses that revoked and expired rows are included (audit-trail scope) and that key material is never returned, a security-relevant guarantee an agent could not infer from the annotation.

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 clipped sentences with zero filler; the scope and the key-material guarantee are both front-loaded and each phrase earns its place.

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?

An output schema exists, so return-value structure needn't be explained. The description still covers the two things an agent would want to know: that revoked/expired entries are included and that no secrets are exposed. Slightly light on when to prefer it over adjacent key/token listing tools, but otherwise complete.

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 the baseline is 4. The description correctly adds no parameter detail, as there is nothing to document.

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 the exact resource ('this project's fsk_ keys') and scopes it to the current project, which distinguishes it from sibling list tools like fillo_list_tokens and fillo_list_sync_tokens by the 'fsk_' key type. The verb is implied by the noun phrase rather than stated, but the operation is unmistakable.

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?

Usage is only implied: the mention of 'revoked and expired rows for the audit trail' suggests this is for auditing/reviewing keys, but it never says when to call this versus related tools such as fillo_revoke_api_key or fillo_list_tokens. No explicit when/when-not guidance is given.

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