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

Goes well beyond annotations by disclosing cost behavior ('paid, credits scale with length'), the quote/confirm (quote_id) safeguard, and free vs. paid modes. It also states a side effect the agent needs: 'Cast ducks music under speech automatically.' It doesn't cover failure/rate-limit behavior, keeping it from a 5.

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?

Dense but every sentence earns its place, and it is front-loaded with the mode breakdown and the free-first recommendation. Slightly overloaded with mode details in one block, but no wasted prose.

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-param, multi-mode, paid-capable mutation tool with no output schema, the description covers the mode semantics, cost model, and downstream handoff well. The main gap is undocumented params (record_mode, wait_seconds) and return shape, but the essentials for correct invocation are present.

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 43%, so the description carries weight: it explains duration_sec (episode length), format_id (from mode:'formats'), query (vibe description), and quote_id (confirm after quote). It does not clarify record_mode, wait_seconds, or maxLength/pattern constraints, so it compensates for much but not all of the gap.

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 states a specific verb and resource ('Licensed Mubert music for the episode') and, crucially, enumerates the four modes (library, formats, curated, generate) with what each does. This lets an agent distinguish the sub-operations without opening the 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?

Explicit when-to-use guidance: 'always try this first, it is free and instant' for library, and 'generate' is flagged as paid with a quote-first flow. It also tells the agent the downstream step: 'Pass the resulting audio_file_id to cast_build_project as music.'

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