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

Annotations already declare readOnly/idempotent/openWorld, so the bar is lower; the description still adds real behavior: sponsor results are only the OpenParliament-indexed subset, an omitted session resolves to the 'verified current official session', and pagination must reuse identical filters. It does not discuss the response-size/byte-budget truncation behavior, though that is covered by the schema.

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?

Four tight sentences, front-loaded with the primary capability, followed by scope caveat, default, and pagination rule. No sentence is redundant or restates the title.

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, annotations covering the safety profile, and full param documentation in the schema, the description supplies exactly the missing connective guidance: sibling routing, sponsor-coverage limitation, session default, and pagination continuation. Nothing needed to invoke it correctly appears absent.

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%, so the baseline is 3; the description earns a point by summarizing which fields act as combinable filters and by flagging the sponsor-indexing caveat and session defaulting in agent-facing terms. It adds no syntax detail beyond the schema (slug formats, billCode variants, status reference topics are schema-only).

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 ('Find') plus the resource ('House and Senate bills') and enumerates the filterable dimensions (title, number, type, chamber, status, indexed MP sponsor). It also explicitly distinguishes itself from the sibling read tool by saying a bill must be fetched for sponsor, stages, divisions, and statute citation.

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 names the alternative path — 'fetch a bill for its sponsor, stages, divisions, and statute citation' — which routes the agent to canparl_get_bill when detail is needed rather than search. It also states the default when session is omitted and the pagination contract ('follow nextOffset with identical filters'), 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.