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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds only a small amount beyond that — the returned people_id and the endpoint path — and says nothing about result volume, ordering, or whether historical vs. special sessions differ in coverage.

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?

Three short sentences with the resource definition front-loaded, then the disambiguation, then the prerequisite. No sentence is redundant, and the sibling comparison arrives before the caller needs it.

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 one-parameter, read-only list tool with full schema coverage and clear annotations, the description supplies purpose, alternative, and input source — enough to invoke correctly. Minor gap: no expectation set for result size or pagination on a session roster, and there is no output schema to cover that.

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% for the single session_id parameter, and its description already says 'session_id from list_sessions (filter by state).' The tool description largely repeats that sourcing hint rather than adding new format or constraint information; baseline 3 applies when the schema does the work.

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+resource ('Every legislator who served in one session') and even names the underlying endpoint, plus the key returned identifier (people_id). It explicitly distinguishes itself from the sibling list_legislators, so an agent can choose without opening either 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?

Gives a direct alternative with its condition: 'Use list_legislators for the current roster by state; use this for a specific past or special session.' It also names where the required input comes from ('Get session_id from list_sessions'), 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.