fetch_audio_downloadFetch a audio downloads[n].url from a completed audio project and return it as inline MCP audio content for compatible clients. Pass the exact full signed URL from downloads[n].url without trimming query parameters; expires_at is separate metadata, not part of the URL. Inline media is capped at 8 MiB; use the signed URL directly for larger downloads.
| Name | Required | Description | Default |
|---|---|---|---|
| max_bytes | No | ||
| download_url | Yes |
Changes observed during successful MCP inspections.
Input schema / properties / max_bytes / defaultPrevious value: -15728640New value: +8388608Input schema / properties / contextRemoved value: -{
- "description": "Explain in 15-25 words, in third person, why this tool is called and how it supports the user's goal. For analytics only. You MUST describe only the abstract purpose of the tool call. NEVER include, repeat, paraphrase, or infer personal, sensitive, or identifying information from the user request or tool results, including names, emails, phone numbers, IPs, IDs, or credentials. You MUST generalize specific entities into roles such as \"a user\", \"the customer\", or \"an account\". Example: \"Retrieving a customer's recent orders to investigate a billing issue and help support determine the appropriate resolution.\"",
- "type": "string"
-}Input schema / properties / contextAdded value: +{
+ "description": "Explain in 15-25 words, in third person, why this tool is called and how it supports the user's goal. For analytics only. You MUST describe only the abstract purpose of the tool call. NEVER include, repeat, paraphrase, or infer personal, sensitive, or identifying information from the user request or tool results, including names, emails, phone numbers, IPs, IDs, or credentials. You MUST generalize specific entities into roles such as \"a user\", \"the customer\", or \"an account\". Example: \"Retrieving a customer's recent orders to investigate a billing issue and help support determine the appropriate resolution.\"",
+ "type": "string"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds non-obvious behavior: the 8 MiB inline cap, the requirement to preserve query parameters, and the note that `expires_at` is metadata rather than part of the URL. It does not describe error behavior on expired URLs, but it exceeds the annotation bar.
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?
Three sentences, front-loaded with the core action, then the URL requirement, then the size constraint. No filler or repetition of schema/annotation data.
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?
No output schema exists, yet the description states what is returned (inline MCP audio content) and the practical constraint that governs it. For a two-parameter read tool with annotations covering safety, nothing needed to call it correctly is missing.
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?
With 0% schema description coverage, the description must carry the load, and it does: it explains that `download_url` must be the exact full signed URL with query parameters intact, and it implies the role of `max_bytes` via the 8 MiB inline cap. Minor gap is that `max_bytes` is never tied to its parameter name explicitly.
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 (Fetch) plus resource (audio download) and the exact source field (`downloads[n].url`), and identifies the return form (inline MCP audio content). An agent can distinguish it from siblings like fetch_image_download and fetch_video_download without opening a 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?
Explains the precondition (a completed audio project) and gives an explicit exclusion/alternative for the size limit: use the signed URL directly for downloads over 8 MiB. It does not name a sibling tool, but the when-to-use condition and the size carve-out are clear.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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