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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed world, so safety is covered. The description adds one genuinely useful behavioral fact — only 'published' credit unions are returned, i.e. an implicit visibility filter — but says nothing about pagination behavior, empty-query results, or how the closed-world hint interacts with country codes outside the directory (a 400 the schema mentions but the description does not reinforce).

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?

A single front-loaded sentence with no filler, which is the right shape for a tool whose parameters are fully documented elsewhere. It is arguably thin rather than wasteful, so the size is appropriate though not maximally informative.

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?

With 8 optional parameters and no output schema, an agent gets safety from annotations and semantics from the schema, but the description never states what happens with zero filters (return all published listings?) or how the no-required-params behavior interacts with the sort defaults. For a search entry point covering text/place/category it is adequate but leaves the empty-query case to inference.

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%: q's matching behavior and typo fallback, sort's default logic per q, cursor's opaque resend semantics, and country's 400-on-uncovered-code are all documented in the schema itself. The description only restates the facets and adds no syntax or interaction detail beyond it, so the 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?

The description gives a specific verb (Search) plus resource (published credit unions) and enumerates the axes it searches on (text, place, category). That separates it from get_listing (single record) and from list_categories/list_places (facet enumerations). It stops short of naming those siblings or explicitly contrasting with them, so it is clear but not fully differentiated.

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?

Usage is only implied: the word 'Search' plus the facet list tells an agent this is the lookup tool, but there is no statement of when to prefer it over list_places/list_categories (which arguably feed its city/region/category params) or get_listing. No exclusions, prerequisites, or fallback guidance are given.

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