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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=true, openWorldHint=false), so the description only needs to add semantics. It does: the band's window length is preserved, and if the band had no window it spans from the given start to the composition end. It does not say what prior start value is overwritten or whether the edit is reversible, which matters for a destructive tool.

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 action is front-loaded in the first clause and every sentence carries information (origin semantics, default span, id provenance). It is delivered as one dense paragraph, so the conditional default-length rule is slightly harder to scan than it could be.

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 not be explained. Given three required params at full schema coverage, the description supplies the missing pieces an agent needs: where bandId comes from, what happens to window length, and the default span when none exists.

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 the baseline is 3, but the description adds real meaning beyond the schema: bandId must come from describe_video and belong to a group with morpha:true, and 'start' is the origin the whole inner reel plays relative to rather than a mere window boundary.

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 – placing an embedded morpha band and setting its time origin on the host timeline – and explains the immediate effect (inner reel plays relative to that frame). An agent can distinguish it from the nearby siblings add_embed_origin, set_embed_origins and remove_embed_origin without opening a 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?

Usage context is given indirectly through the stated problem it solves ('the fix for "the embedded intro doesn't animate"'), which tells the agent when this tool is the right call. It also tells the agent how to obtain the required bandId from describe_video. It never explicitly names an alternative tool or an exclusion, so it falls short of a 5.

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