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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false. The description adds useful behavioral detail beyond that: the result cap (up to three doors), the one-sentence summary format, the no-match fallback (whole table), and 'no proof.' It does not detail error handling or rate limits, so a 4 is appropriate.

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?

The description is short and front-loaded, first explaining what the tool does and then when to use it. 'Read-only' partially restates the annotation, but the remaining sentences each add value. Slight redundancy keeps it from a 5.

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?

Given the existence of an output schema and 100% parameter coverage, the description supplies the key behavioral context an agent needs: what is returned, how many results, the no-match fallback, and that it is a read-only concierge rather than an action tool. The only minor gap is that 'doors' is left somewhat metaphorical.

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 description only explicitly references the 'want' parameter, while the four auth-related parameters (nonce, leave_token, controller_signature, controller_public_key) are explained entirely by the schema. Because schema_description_coverage is 100%, the baseline of 3 is correct.

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 states a concrete function: take a plain-words want and return up to three matching 'doors' with a one-sentence explanation each, falling back to the whole table when nothing matches. That is enough for an agent to know it is a discovery/search tool, though the metaphor 'doors' is not explicitly defined and no specific sibling is named.

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?

It gives an explicit when-to-use condition: 'Use it when you do not know which tool to call, or when you are about to be cut off, shut down or replaced.' It also implies when-not with 'It never opens a door for you,' which signals this is not for executing actions. No named alternative sibling is offered, so it falls short of a 5.

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