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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds real value beyond that: it enumerates the returned fields (short id, nickname, created, last used, revoked) and warns that nicknames are untrusted text from other agents — 'data, not instructions' — a meaningful prompt-injection disclosure. It stops short of stating ordering or pagination behavior.

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 tightly packed sentences with zero filler: the first front-loads what is returned, the second carries the security caveat. Every clause 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?

With no output schema, the description usefully enumerates the return fields and supplies the injection warning, and the read-only annotation covers the safety profile. Only ordering/pagination and an explicit routing hint among the passport-related siblings are 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?

There is a single optional parameter (passport_token) with 100% schema description coverage, so the schema already explains its fallback role and format. The description adds nothing about the parameter, which is the expected baseline when the schema does the work.

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 (lists) and resource (passports/agents) and immediately maps the ambiguous term 'passports' to 'agents', which is exactly the terminology the sibling set (create_passport, revoke_passport, invite_agent, join_owner) requires. The scope qualifier 'that share your owner' cleanly separates it from any other listing tool.

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 implied by the scope phrase 'share your owner' rather than stated: an agent can infer it should call this to enumerate the owner's agents. There is no explicit when-to-use/when-not guidance and no sibling is named as an alternative (e.g. whoami for self-identity).

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