lookup_watched

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

With no annotations, the description carries the disclosure burden and does well: it states this queries Simkl directly, returns a parallel array with library status and last-watched time, and is independent of the local mirror. It does not cover error cases or authentication, but the key behavioral traits are disclosed.

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?

The description is compact and well ordered: purpose, input format, output behavior, then rationale. Every sentence adds useful information, and there is no redundant filler.

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?

The tool has only one parameter, the description explains its shape and the output in broad terms, and an output schema exists so return details need not be repeated. It is complete enough for selection and invocation, though minor edge-case behavior such as invalid ID keys is not addressed.

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 0%, so the description must compensate, and it does. It explains that 'items' is a list, shows an exact example with simkl and imdb ID keys, and clarifies that any mix of supported ID keys is accepted. This goes well beyond the minimal array-of-objects schema.

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 'Ask Simkl directly whether specific titles are already in the library,' a specific verb and resource. It further distinguishes itself by noting this is a server-side check independent of the local mirror, separating it from sibling tools like get_library and get_library_ids.

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?

The description gives clear usage context: it is the server-side check behind the 'never already seen' guarantee and is independent of the local mirror, catching activity since the last sync. It implies when to prefer this tool over local-mirror lookups, though it does not explicitly name alternatives or say when not to use it.

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