select_subframes

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

The description openly discloses that the tool writes SSWEIGHT into approved frames and specifies the output directory, which goes beyond the annotations. It also states what is returned (approved/rejected with reasons and the spread), which is especially valuable because no output schema is present.

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 substantive information: what the tool does, what it returns and writes, and a caution for edge cases. No filler or redundancy.

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 description conveys the input context, filtering logic, return values, side effects, and output location, which is strong given no output schema. It could more explicitly state that this step should run after measure_subframes and before integration, but 'measured frames' strongly implies that workflow position.

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?

With 50% schema coverage, the description compensates by grouping the explicit limit parameters (max_fwhm, max_eccentricity, min_stars, min_snr_weight) and explaining the relative rule as fwhm_factor × median. The schema already documents dry_run, reject_indexes, and defaults, so combined understanding of the parameters is solid.

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 operation (Approve/reject measured frames) and clearly distinguishes it from measuring or integrating tools by focusing on selection with quality limits. It lists the exact rule mechanisms, leaving no ambiguity about what the tool does.

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 phrase 'measured frames' establishes the prerequisite that measurement must already have happened, and the caution about being reluctant to reject with fewer than 20 frames is practical usage guidance. It does not explicitly name alternatives or when-not conditions, but the context is clear enough.

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