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

With no annotations, the description carries the full burden. It does disclose one meaningful trait beyond the schema — 'always re-encoded', which warns the agent that output is lossy/reslowered rather than stream-copied. It omits other behavioral facts a mutation tool should state: that output is written to a new path (overwrite semantics are only in the schema), whether source files are modified, and what quality/profile the re-encode uses.

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?

A single front-loaded sentence with no filler; the two operative constraints ('one file', 'always re-encoded') appear immediately.

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?

No annotations and no output schema mean the description must carry behavioral context, and it covers only the re-encode trait. For a four-parameter media-writing tool, it should also state that nothing is written unless output path is set, how overwrite interacts with an existing file, and how it differs from trim before an agent can call it confidently.

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 100%, so every parameter including segment start/end units and the overwrite default is already documented in the schema. The description's 'in order' duplicates the schema's 'Ranges to keep, in output order' and adds no new parameter meaning, making the baseline 3 appropriate.

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: keeps listed ranges of one file and joins them. The phrases 'one file' and 'in order' implicitly separate it from the multi-file concat sibling, but no sibling is named, so an agent must infer the boundary with trim/concat.

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?

Usage is only implied: the tool is for extracting multiple ranges from a single source. There is no explicit statement of when to prefer it over trim (single segment) or concat (multiple files), and no prerequisites or exclusions are given.

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