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

Annotations already cover the safety profile (read-only, idempotent, closed-world), and the description still adds substantial behavior: a hard cap of 25 matches, ranking with exact titles first, the per-result fields, and the meaning of known_as. It even predicts a silent-empty-result failure mode by warning that sub-three-character queries require an exact title match.

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 sentences, each carrying distinct information, with the resource scope and match rule front-loaded before the result-shape notes. No filler, no restatement of the tool name or the enum values already in 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?

There is no output schema, so the description must explain returns, and it does: match count limit, ordering, per-item fields, and the known_as note. Combined with a fully documented two-parameter schema and complete annotations, nothing needed to call or interpret this tool is missing.

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 schema already explains kind's enum and query's bounds; the baseline would be 3. The description earns an extra point by defining matching semantics the schema does not: case-insensitivity, which fields are searched (title, original title, other title), and the special behavior for very short queries.

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 names a specific action (match by substring) over specific resources (films, people, scores) and constrains it to title fields, which cleanly separates it from the renoir_get_* siblings that fetch by id. An agent can tell this is the discovery/ID-lookup entry point without opening any 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?

Usage is only implied: the agent must infer that this is the way to find an entity before calling renoir_get_entity or renoir_get_film, since no sibling is named and no when-not condition is given. The short-query caveat (under three characters matches a whole title exactly) is genuinely useful guidance, which lifts it above a pure 2.

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