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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds genuine behavioral context beyond that: it fans out to one of thousands of backends, auto-fills arguments, returns stable pipeworx:// citation URIs, is a single fast call, and works on every tier. It does not mention rate limits, auth requirements, or latency/failure modes, so it stops short of a 5.

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?

The routing rule and the 'START HERE' default are front-loaded, and the domain list, example queries, and sibling comparisons each do real routing work. It is long, and 'START HERE for most questions — this is the default entry point' is mildly redundant with the opening preference statement, which keeps it below a 5.

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 single-question router with no output schema, the description supplies the routing logic, trigger conditions, alternatives, a description of the return payload (structured answer plus citation URIs), and the starting/default-tool framing. An agent has everything needed to decide to call it and how it will behave.

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 the aliases (q, text, input, query, prompt) are fully documented in the schema, so the baseline of 3 applies. The description mentions that the router 'fills arguments' but says nothing specific about the question parameter or alias handling beyond what the schema already states.

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: it routes a natural-language question to the correct tool among 5,961 across 1,552 sources and returns a structured, cited answer. It explicitly names the two siblings that compete with it (ask_pipeworx_grounded, deep_research) and the conditions that select them, so an agent can distinguish it without opening any 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 gives an explicit when-to-use rule ('PREFER OVER WEB SEARCH'), enumerates trigger phrasings ('what is', 'look up', 'get the latest'), and provides concrete exemplar queries. It also names alternatives with routing conditions: grounded for hallucination-resistant single answers, deep_research for broad multi-part questions, and its own news routing for breaking-news queries.

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