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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description adds genuinely useful context beyond structured fields: the response includes a top-level `connectors` array of the user's connected SaaS accounts, with an example of how to use it. It does not discuss pagination or result limits, keeping it at a 4.

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?

Front-loads the purpose and then the routing flow. It is somewhat dense and repeats the category list already in the schema enum, which is minor redundancy, but every sentence is otherwise 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?

No output schema exists, so the description carries the return-value burden and does so by explaining the `connectors` array and that exact-name queries return schemas. Combined with annotations covering safety and the 100%-covered input schema, an agent has what it needs; only return format details are thin.

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 the baseline is 3. The description goes further by clarifying query semantics the schema does not: an exact tool name (e.g. "seo") returns full schemas and examples, and it supplies natural-language query examples plus the category list, adding real meaning.

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 and resource: "Find the right ToolRouter tool for your task." It distinguishes itself from siblings by naming route and use_tool and explaining its distinct role (schemas/listing) in the flow.

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?

Explicit routing guidance: "prefer route({ intent }) to pick and run a tool. Use discover when you need schemas or a listing, then call use_tool(tool, skill, input)." This names the alternatives and the exact conditions that select each, leaving nothing to inference.

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