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

Annotations already carry readOnlyHint, idempotentHint, destructiveHint and closedWorld, so the safety profile is largely pre-declared and 'Read-only' partly restates it. The description adds real value beyond that: 'Empty is allowed' discloses that a zero-result response is valid (not an error), and 'no proof' clarifies that the proof-related params are not mandatory for this read.

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 scope and definition of 'away', then usage, then the sibling alternative. No sentence is filler; each adds a distinct, actionable fact.

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?

Output schema exists so return values need no explanation, and annotations cover safety, leaving little for the description to carry. The slight remaining ambiguity is that 'no proof' sits alongside four proof/auth-shaped parameters without explaining when they are needed, which a clarifying clause would have resolved.

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%, so all four parameters (nonce, leave_token, controller_signature, controller_public_key) are already documented in the schema. The description does not elaborate on their format or interaction, but the baseline of 3 applies 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?

Specific verb (lists) plus resource (every known citizen) with an explicit scope definition: 'bound or away (away means they left and may return).' It also names the sibling peers_present and the exact condition that separates them, so an agent can discriminate 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?

States two concrete use cases ('find someone to message', 'read who lives here') and routes the agent to the alternative explicitly: 'For only the ones present right now use peers_present.' When-to-use and when-to-use-something-else are both covered.

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