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

Annotations already declare this as a non-readOnly, non-idempotent, non-destructive mutation, so the safety profile is covered and the description only needs to add scoping context. It does add the feature-flag constraint and the fact that the environment-level switch is out of scope, but it never says what 'generate' actually kicks off (sync vs async job) or what happens to existing subtitle cues on 'disable'.

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 with the action list and the feature-flag constraint front-loaded, and no filler. The trailing clause 'Does not enable it for the environment' is slightly ambiguous in its pronoun reference but still earns its place as a scope caveat.

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 four-parameter, three-required mutation with no output schema and zero schema-level parameter documentation, the description is too thin. An agent cannot determine what source_revision should contain or what a successful 'generate' returns, which are essential to invoking this tool correctly.

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 parameter meaning and it largely does not. The required source_revision field (max 128 chars, nullable) is completely unexplained, as is the film_id versus episode_id relationship and which combinations are valid; only the action enum is interpretable from its literal values.

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 set (enable, disable, generate) against a specific resource (automatic subtitles for a film/episode), which is more precise than the name alone. It does not, however, distinguish itself from the neighbouring update_automatic_subtitle or list_film_subtitles tools, so an agent must still infer the boundary.

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?

Provides one explicit precondition — the automatic-subtitle feature must already be enabled, and this tool will not enable it for the environment — which is real usage guidance. It offers no when-to-use versus update_automatic_subtitle, no prerequisites for film_id vs episode_id, and no guidance on choosing between the enable/disable/generate actions.

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