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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true. The description adds genuine context by revealing the router behavior and, crucially, that the tool 'fills arguments' itself — telling the agent to pass a natural-language question rather than parameterize. It also discloses the citation-URI return trait; no contradiction with annotations.

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 roughly 250-word description is long but unusually information-dense: it front-loads the critical routing decision ('PREFER OVER WEB SEARCH'), then proceeds What → When → Examples → When-not. There is minor redundancy between the 'Use whenever...' trigger list and the closing 'START HERE... unless...' exclusion, so it isn't perfectly lean.

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 complex router (5,798 tools, no output schema) with a single required param and strong safety annotations, the description is nearly complete: purpose, usage, exclusions, alternatives, examples, and the return shape (structured answer with pipeworx:// URIs). The remaining gaps are minor — the exact answer structure and behavior when no source matches are left unspecified.

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% — all six params are documented as aliases of 'question'. The description adds example queries and implies only the free-text question matters ('fills arguments'), but it doesn't specify format or constraints beyond what the schema provides. Baseline 3 is appropriate since the schema fully carries the parameter documentation burden.

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 the question to the right one of 5,798 tools across 1517 verified sources, fills arguments, returns the structured answer with stable pipeworx:// citation URIs.' This is no tautology and clearly differentiates it from siblings like search, lookup, and deep_research by establishing it as a meta-router over authoritative data sources.

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?

Explicitly opens with 'PREFER OVER WEB SEARCH', enumerates trigger phrases ('what is', 'look up', 'get the latest', 'current'), gives six concrete examples, and states exclusions: 'unless you already know the specific source/tool to use, or the question requires live, unverified, or real-time data' — then names alternatives ('web search... or other tools'). This is textbook when/when-not/alternatives guidance.

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