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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the bar is lower. The description nonetheless adds real context: it is a dry run that doesn't mutate audio, sources combine, and it describes its return payload (merged cuts plus text removed and resulting length), which annotations do not cover.

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 purpose, then the source enumeration, then the return/next-step. Dense but each clause carries information; the parenthetical examples earn their space by clarifying parameter format. Slightly heavy on parentheticals.

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?

With no output schema, the description takes on the return-value burden and does so (merged cuts, removed text, resulting length), and it explains source-combination semantics and the downstream handoff. Minor gaps remain, such as default marker toggles and behavior when no cuts are found.

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 only 33%, so the description must compensate, and it does: it defines the four source parameters (markers, phrases, word_ranges, ranges), gives a phrase example, and anchors word_ranges to cast_get_transcript format:"words". Only exclude_ranges remains purely schema-documented (though its own schema description covers it).

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 ('Builds a cut list') and immediately scopes it as a dry run that doesn't touch audio. This cleanly separates it from its downstream sibling cast_build_project, which applies the cuts.

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?

Provides clear context — build the list, review, then pass `cuts` to cast_build_project — and explains that the `markers` source re-runs cast_analyze, tying it to sibling behavior. It stops short of stating when to prefer a different approach, but the workflow placement is unambiguous.

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