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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does disclose a key behavior: 'keeping original timecodes' and that the tool returns one half via the 'part' parameter. However, it does not detail edge cases, error behavior, or potential side effects (e.g., whether the original track is preserved). This is adequate but not exhaustive.

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?

The description is only two sentences with no filler. The core purpose and behavioral note are front-loaded, followed by a direct usage hint. Every word contributes meaning.

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?

Given the tool's complexity (split at timecode, return a part) and the absence of an output schema, the description sufficiently communicates how to call it correctly. It mentions the key output behavior (fetch either half) and relies on the schema for parameter details. Minor gaps like inclusivity of the split point or return format are not critical for invocation.

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% (all parameters have descriptions). The description adds semantic value above the schema by explaining the interplay between 'at' and 'part' ('Use the at argument plus part to fetch either half'), which is not explicitly stated in the parameter descriptions. This exceeds the baseline of 3 for high coverage.

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 clearly states the tool's function: 'Split one subtitle track into two parts at a given timecode, keeping original timecodes.' It specifies a verb (split), a resource (subtitle track), and a precise operation (split at a timecode). It also distinguishes itself from sibling tools like merge_subtitles or retime_subtitles without ambiguity.

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 description provides clear context on how to use the tool ('Use the at argument plus part to fetch either half') which guides invocation. It does not explicitly mention when not to use it or name alternatives, but the purpose is self-evident given the siblings. This qualifies as 'clear context, no exclusions'.

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