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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description still adds real behavior not in the annotations: results are limited to 'public' details, and invalid/unavailable/withdrawn IDs produce an error rather than empty data. It does not cover auth requirements or rate limits, so not 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?

Two sentences, zero filler, with the core action and ID provenance front-loaded and the error behavior trailing. Every sentence carries distinct information.

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-parameter read tool with no output schema, the description covers what the tool returns (public plan details), where the input comes from, and the failure mode. The only gap is that with no output schema an agent cannot anticipate which detail fields come back, but that is a minor omission for this complexity level.

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 0%, so the description must carry the load; it does by stating provenance ('returned by search_plans'), which is the key semantic an agent needs for supplying plan_id. Format constraints (pattern, length) are enforced by the schema but not restated, and there is only one parameter, so this is close to fully compensated.

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 opens with a specific verb and resource ('Read current public details for a plan ID') and scopes it to public/current data. It implicitly separates itself from search_plans by positioning that sibling as the ID source, though it never states the contrast directly (e.g., 'use search_plans to discover, this to fetch one').

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 establishes a clear workflow precondition: the plan_id must come from search_plans, which tells an agent when this tool is the right call. It also states the failure condition (unavailable/withdrawn plans error out). No explicit when-not-to-use or alternative fetch mechanisms are given, keeping it at 4 rather than 5.

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