still_match

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

With no annotations, the description carries the full burden and does well: it states sources are not overwritten (non-destructive), that matched stills plus a JSON receipt are written under output_dir, and that per-frame auto-WB is disabled so only shared gains apply. It stops short of error behavior or any permission/dependency notes.

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?

Front-loaded purpose sentence, followed by two short behavioral constraints, then a compact Args block. The Args section is not mere repetition of the schema because it adds the 'absolute path' semantics, so every line earns its place.

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 the required fields, write behavior, and non-destructive guarantee are covered. What remains unaddressed is failure/error handling and any environment or permission assumptions for a file-writing tool.

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%, yet the Args block documents all three parameters with real meaning: hero is the absolute path to the hero/establish still, inputs are absolute paths to the package stills, and output_dir is the absolute directory for outputs and receipt. This fully compensates for the empty schema descriptions.

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 and resource ('Match a package of stills to a hero plate') plus the exact mechanism ('one shared WB/exposure gain'). This clearly distinguishes it from nearby siblings like still_grade, still_gate, and still_package. An agent can identify the operation without opening the 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?

The scenario is implied by the purpose statement (color-matching a stills package to a hero plate), which is enough to infer when it applies. However, it never names an alternative or exclusion among the still_* siblings, nor states prerequisites, so routing is left to inference.

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