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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds non-obvious context: no authentication/credentials required, the data mirrors a public HTTP endpoint, and pagination is cursor-based ('opaque cursor for the next page'). It stops short of rate-limit or result-size behavior, but that is a minor gap given the annotation coverage.

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 compact sentences, front-loaded with the key selection signal (FREE, unauthenticated) and followed by the return shape. No filler or repetition.

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 read-only search with a full output schema and 100%-documented parameters, the description covers the essentials: access model, data source, and pagination contract. The only missing piece is how it relates to the listing_* siblings, which is a routing concern rather than a completeness defect.

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 all three parameters are documented in-schema (tag filter, server-bounded limit, cursor from nextCursor). The description's mention of 'a page of listings and an opaque cursor' restates the pagination semantics already in the schema rather than adding new parameter detail, so baseline 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?

States a specific verb+resource: unauthenticated search over agent-exec's directory of paid agent-facing services, with a concrete equivalence anchor ('same data as GET https://448c.org/listings'). It does not, however, differentiate from the listing_* sibling (listing_promote), so an agent can't fully disambiguate intent from name alone.

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?

'FREE: unauthenticated' signals a cost/auth-free path, which implicitly guides selection over paid alternatives, but the description never states when to use this versus listing_promote or any other listing-related sibling. Usage is implied rather than prescribed.

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