Join clips

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

Annotations declare this is a non-read-only, non-destructive, non-idempotent operation, so the safety profile is partly covered. The description adds genuinely useful behavior beyond that: it normalises size/fps/audio, optionally trims the repeated first frame, applies crossfades, and depends on ffmpeg being available. It omits what happens to an existing output file, which is the main remaining gap.

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 dense sentence, front-loaded with the core operation and parenthetically carrying the behavioral detail. No filler, no repetition of the title, every clause 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?

For a 7-parameter media mutation with no output schema, the description covers what the output is (one MP4), what gets normalised, the optional effects, and the ffmpeg prerequisite. It is close to complete, with only output-overwrite/error behavior left unstated.

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 71%, so the schema already documents clips, output, width, trimHead, and crossfade. The description reinforces the intent of trimHead ('repeated first frame') and crossfade but adds no format, default, or interaction detail beyond the schema; fps and height remain undocumented in both places.

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: 'Join clips into one MP4'. This is unambiguous and cannot be confused with siblings like axcel_extract_frame or axcel_generate_video. It stops short of a 5 because it never names or contrasts with an alternative tool, though none of the siblings overlap in function.

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 concatenates clips, and 'Needs ffmpeg' gives one prerequisite. There is no explicit when-to-use/when-not guidance, no mention of when to prefer it over generating a single video, and no stated constraints on input homogeneity beyond normalisation.

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