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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds nothing beyond that: it does not explain what 'similar' is based on (genre, director, user co-occurrence), whether an unknown slug errors or returns empty, or that limit is capped. With annotations present the bar is lower, but zero added context still warrants a low score.

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 words with no filler and nothing to trim, but it is a fragment rather than a front-loaded sentence, and its brevity stems from under-specification rather than disciplined editing.

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?

An output schema exists, so return values need no explanation, and both parameters plus the read-only/open-world annotations are fully covered by structured fields. For such a simple two-parameter read tool the definition is minimally viable, though it leaves the meaning of 'similar' and the slug's provenance unexplained.

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 100% — the slug format ('parasite-2019') and the limit default (10) with max (50) are fully documented in the schema. The description adds no parameter meaning beyond that, so the baseline of 3 applies.

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 is a noun phrase, 'Letterboxd similar films.', that merely restates the tool name letterboxd_film_similar without a verb or scope. It does not distinguish this tool from siblings like letterboxd_film, letterboxd_popular, or letterboxd_search.

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?

No when-to-use guidance, no prerequisites (e.g. 'requires a valid film slug obtained from letterboxd_search'), and no mention of alternatives such as imdb_title_similar or tmdb movie lists. The agent must infer the entire usage context.

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