fetch_image_downloadFetch a image downloads[n].url from a completed image project and return it as inline MCP image 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, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the 8 MiB inline cap, the requirement to pass the untrimmed signed URL, and the note that expires_at is separate metadata rather than part of the URL.
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 tight sentences, front-loaded with the core action and output, followed by the URL-passing rule and the size limit. Every sentence adds a constraint the agent needs.
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 correctly explains the return type (inline image content for compatible clients) and the size/URL constraints. It is nearly complete; error behavior for expired URLs or non-image content is not covered, but that is a minor omission for a read-only fetch tool.
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 0%, so the description carries the burden, and it does: download_url must be the exact full signed URL with query parameters intact, and the 8 MiB cap maps directly to max_bytes (default 8388608). It does not explicitly define max_bytes' unit or that it overrides the inline cap, leaving a small 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 (Fetch), resource (image download URL from a completed image project), and output form (inline MCP image content), which clearly separates it from fetch_video_download and fetch_audio_download in the sibling list. An agent can pick this tool 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?
It gives a clear precondition ('from a completed image project') and a when-not branch ('use the signed URL directly for larger downloads' beyond 8 MiB). It does not explicitly name the sibling fetch tools or the wait_for_image_project prerequisite, so routing context is implied rather than spelled out.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.