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

Annotations already declare read-only/idempotent/closed-world, and the description still adds real behavioral context: returns a JSON array of full entities, [] means no match, fields trims payloads, and data is limited to Episodes I-VI. That last point independently corroborates openWorldHint=false and sets an agent's expectation about coverage gaps.

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 imperative 'Start here', each carrying distinct information: matching rule, example, return shape, downstream id derivation, and data scope. No redundancy with the schema.

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 no output schema, the description fully compensates by describing the array return, the empty-array convention, field projection, and the url-to-id mapping. The Episode I-VI scope note closes the remaining gap an agent would otherwise hit silently.

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%, so the baseline is 3; the description still adds value by showing a worked query example and by explaining that the id needed downstream is embedded in the url field rather than returned as a top-level key. It does not restate the fields-count limit or enum error behavior, which the schema already covers.

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 (finds), resource (Star Wars entities) and the matching rule (case-insensitive substring, with 'title' for FILMS). The concrete 'sky' example makes the semantics unambiguous and separates it from sw_get, which the description explicitly routes to.

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?

'Start here' gives an explicit entry-point instruction, and 'The id to pass to sw_get is the last segment of each entity's url field' defines the handoff to the obvious follow-up tool. There is no explicit 'use sw_list/sw_random instead when...' clause, so it falls short of full when/when-not guidance.

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