list_elevenlabs_voices

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

With no annotations provided, the description carries the full behavioral burden and does well: it discloses the auth source (ELEVENLABS_API_KEY env var of the MCP server), the privacy behavior (key used for this call only, never stored), and the cost model (free, no PageBolt request charged). It omits error/failure modes and rate-limit behavior, which keeps it short of 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?

Four short sentences, front-loaded with the purpose and followed by auth, cost, and a preference tip. Nothing is redundant padding, though the cost and BYO-key notes could be tightened slightly.

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 and no annotations, the description still covers the essentials an agent needs: what it returns (a voice list), the credential source, the fact that it is free, and how the result feeds into record_video. Only return-shape details (id/label fields) are left to inference, which is minor for a one-param lookup.

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% — the single 'search' parameter is already documented with format and examples in the schema. The description adds no additional meaning about that parameter, so the baseline 3 is appropriate; the downstream field mapping it does provide concerns record_video, not this tool's input.

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 — 'List the voices in the user's OWN ElevenLabs account' — and clarifies it is the user's own account via BYO key. It ties the result to a concrete downstream field (audioGuide.elevenlabs.voiceId for record_video with provider "elevenlabs"), which cleanly separates it from every sibling.

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?

Explicitly says what the tool is used for (picking a voiceId before recording) and gives a selection heuristic ('for a product demo, prefer a calm narration/explainer voice'). There are no explicit when-not conditions, but no sibling offers an alternative voice-listing capability, so the routing context is effectively complete.

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