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

No annotations are provided, so the description carries the full disclosure burden. It does add real context: this is a fallback source, it needs no select_site, and each action maps to a scope of output (catalog vs fragments vs full spec). However it says nothing about read-only nature, caching, rate limits, or response size for full spec fetches, which is material for a fetch-heavy tool.

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 short, front-loaded sentences: the resource and location first, then the fallback routing rule, then the action glossary. Dense but every clause earns its place. The telegraphic style ('… schemas', 'list — catalog') is terse but readable.

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 5-parameter lookup tool with no output schema and full schema coverage, the description supplies the routing context (when it is the right tool) and the action semantics an agent needs. Absent only secondary detail like caching or response size, which is not required to call it correctly.

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%, so every parameter (url, limit, query, action, module) is already documented in the schema, including the action enum semantics and the module examples. The description restates the action breakdown rather than adding syntax, format, or edge-case meaning beyond it. 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 names a specific resource (the OpenAPI YAML reference at api.ucoz.net/{module}-openapi.yaml) and frames it as a fallback, distinguishing it from the primary content_tool/users_tool/shop_tool schemas. The three action verbs (list/search/fetch_spec) are enumerated, so an agent knows what it can do. It stops short of a single crisp verb+resource statement, but purpose is clearly inferable.

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 only when a rare uAPI key is missing from content_tool / users_tool / shop_tool / … schemas'), which is the strongest form of routing guidance available. It also adds a prerequisite note ('Does not require select_site'), useful given select_site is a sibling tool. It lacks explicit when-not-to-use beyond the fallback framing, so not a 5.

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