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

Annotations already cover the mutation/safety profile (readOnlyHint=false, idempotentHint=false, openWorldHint=true), so the bar is lower. The description adds genuinely new context: this kicks off a background job ('A job, usually done in under half a minute'), which tells the agent the call is asynchronous and fast rather than synchronous. It does not contradict any annotation.

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 with the core action and effect/parameter mapping in one dense sentence, followed by two short supporting sentences. 'POST /music/edit operation effect' is mildly cryptic technical noise, but overall there is little waste.

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 15-parameter mutation tool with no output schema, the description covers effect selection and job latency but omits how the produced clip is retrieved (e.g., via flowmusic_get_job) and what happens to errors or partially specified effects. Adequate but with clear gaps.

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 100%, and the schema already labels each parameter with its effect (e.g., 'Reverb: wet mix, 0-1'). The description's grouping of parameters by effect largely repeats that mapping, adding only navigational convenience rather than new meaning, so the baseline of 3 applies.

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 ('Apply one effect to a clip') and enumerates the six supported effects with their parameter groups, so the agent immediately knows the scope. This distinguishes it from siblings like flowmusic_split_stems or flowmusic_replace_section, which operate differently on clips.

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?

'Each effect reads only its own parameters' is a concrete rule that prevents an agent from passing irrelevant fields, and the clip schema text points to where clip ids come from. However, there is no explicit when-to-use vs. alternatives guidance or statement of prerequisites (e.g., account/source-required).

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