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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds behavior beyond that: it is a public-record view only, it lists the specific payload the agent can expect despite there being no output schema, and it notes the 'View listing on Parksy' link is where the user contacts the provider. Not covered: failure behavior for an unknown id or malformed URL.

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 sentences, front-loaded with the resource and its payload, then the input sourcing. The field enumeration is dense but earns its place because no output schema exists.

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 zero-required-parameter, two-alternate-input read tool with no output schema, the description does the heavy lifting by previewing the returned fields and the provider-contact link. Minor gap: it never says what to do when both url and listing_id are omitted or which takes precedence.

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%, and the schema already says the URL is used 'instead of listing_id'. The description reinforces the either/or choice and the provenance of listing_id, but adds no format, precedence, or validation detail beyond the schema, so the baseline of 3 applies.

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 and resource: 'Public details of one Parksy parking listing', followed by an explicit enumeration of the fields returned (title, address, prices, space type, features, vehicle sizes, description, link). It is clearly a single-listing lookup, which distinguishes it from the sibling search_parking that produces the ids.

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 tells the agent exactly what to feed it — a listing_id from search_parking or a parksy.com listing URL — which establishes the upstream workflow. It does not state any when-not-to-use condition or what happens if neither identifier is supplied, so it stops short of a full routing statement.

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