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

Annotations only give generic hints (readOnlyHint=false, idempotentHint=false, openWorldHint=true). The description adds the crucial traits they don't convey: no fallback to rendering, an all-or-nothing single round trip, and that quota is still consumed — matching the non-read-only annotation without contradicting it.

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 single-line purpose, then two tight paragraphs covering the trade-off and the quota caveat. No sentence is wasted and the alternative is named before the reader has to infer anything.

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, and the description fully covers failure semantics, cost, and tool selection. The remaining gap is the four undocumented optional parameters, which is a genuine but bounded omission.

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 only 33%: duration and playlist_index are documented in the schema, but mode, format, bitrate, and intensity are undocumented in both places. The description adds no parameter meaning whatsoever, so it fails to compensate for the coverage 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?

States a specific verb+resource ('take a pre-rendered track from the store') and immediately contrasts it with the sibling generate_track. An agent can distinguish the two without opening either 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 ('predictable latency matters more than exact parameters — a live demo, an interactive UI') plus the explicit when-not ('reach for this one only when waiting is worse than failing') and the named alternative generate_track with its differing fallback behavior.

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