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

Beyond the annotations (readOnly, idempotent, non-destructive, open-world), the description discloses the runtime checks performed ('checks the listing is to let and still available') and what does not happen ('Creates nothing — the applicant signs in and completes the application'). The data-handling prohibition on collecting employment, income or ID details in conversation is a behavioral constraint no annotation conveys.

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?

Three sentences, front-loaded with who the tool is for, then the behavior, then the guardrail and routing. Dense but every sentence earns its place; the nested parentheticals in the first sentence make it slightly harder to scan than an ideal definition.

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?

For a single-parameter, read-only tool with no output schema, the description covers the audience, the precondition, the availability check, the return value (application link), the non-effects, and the follow-up routing. Nothing an agent needs to invoke it correctly and handle the response is 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?

Schema coverage is 100% and the single parameter is already documented as 'Property id of a listing to let', so the schema carries most of the burden. The description adds genuine value by specifying where the value comes from (property_id from search_properties) and constraining it to listings that are to let.

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 and resource ('start a tenancy application') for a specific audience ('someone who wants to rent a specific OpenMoov listing'), and names the exact precondition and return value ('returns the link to the application form'). It also implicitly separates itself from search_properties by naming it as the source of property_id, and from book_viewing by routing unseen-property users there.

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?

Gives an explicit prerequisite chain: 'Use book_viewing first if they have not seen the property', and scopes input provenance to property_id from search_properties. It also states a firm exclusion — never collect employment, income or ID details in conversation — which tells the agent where this tool's responsibility ends.

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