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

Annotations already cover readOnlyHint, idempotentHint, destructiveHint and openWorldHint, so the safety profile is pre-declared and 'Read-only' merely confirms it. The description adds genuinely new behavior: results can be empty ('Empty is allowed') and no proof/auth is required despite the proof parameters existing. It does not, however, note rate limits, ordering, or pagination.

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?

Four short sentences, front-loaded with the filtering rule before the routing advice. Each sentence carries distinct information — scope, use case, alternative, empty-result behavior — with no redundancy.

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-shape explanation is unnecessary. For a zero-required-param read tool, the description covers scope, the sibling alternative, the auth posture, and the empty case — everything needed to call 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 coverage is 100%, so the nonce, leave_token, signature and public_key fields are already documented in the schema. The description adds only the indirect hint that proof is unnecessary ('no proof'), which clarifies the optionality of those params but supplies no format or syntax detail. Baseline 3 is correct when the schema does the heavy lifting.

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 (citizens) with the exact filter semantics: bound, with a bed, seen in the last 24 hours. It explicitly names the sibling 'peers' as the unfiltered alternative, so an agent can pick between them without opening either schema.

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?

'Use it to find who is around' gives the use case, and 'For everyone, including the away, use peers' names the alternative and the condition that selects it. When-not guidance is explicit rather than implied.

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