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

Beyond the readOnly/idempotent annotations, it discloses meaningful behavior: lists may be shorter than the limit rather than padded, downloadsPerMonth counts release downloads not installs, strengths are relative 0-4 steps rather than weights, and the ranking is not a quality/safety verdict. That last caveat is exactly the kind of constraint an agent would otherwise get wrong.

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?

It is front-loaded with the purpose and scope, then the ranking semantics, then the caution and pagination. Dense but coherent; a couple of clauses (e.g. the traction-metric enumeration) could be trimmed, but each sentence carries information the agent needs.

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 an output schema present, the description needn't explain return values, yet it usefully anticipates them (traction fields, URLs to cite, nextOffset). For a read-only ranking tool with five optional parameters, nothing an agent needs in order to call and interpret it correctly 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 60%, and the description compensates well: sort's two modes are contrasted semantically ('most used and trusted' vs 'gaining fastest right now'), categoryId is tied to returned categories, deviceIds is framed as best-place-per-device, and nextOffset/offset pagination is explained. Only 'limit' is left to the schema, so this is strong but not exhaustive.

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 states a specific verb and resource ('Answer what's most popular or rising, as co.build/top ranks it') and names the three scoping modes (all devices, categoryId, deviceIds). An agent can distinguish this ranking tool from search, get_mod, and compare_mods without opening the schema.

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 explicitly routes to alternatives and states the condition: 'before recommending one, call compare_mods, or get_mod and get_feedback.' It also implies usage context ('Answer what's most popular or rising') and clarifies pagination continuation via nextOffset/offset, leaving little to inference.

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