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

Annotations already carry the safety profile (readOnlyHint=true, destructiveHint=false), so the description builds on that with the return contract ("Returns one mcp_upload_id per file"), the batch scope of the token ("the token covers all files they dropped on the page"), and recommended call timing. It adds real behavioral context beyond annotations, though it stops short of specifying container format or pagination. No contradiction with annotations.

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 (~48 words) with zero filler. The first sentence states the core purpose, and each subsequent sentence earns its place: return shape, routing to consumers, call timing, and token scope. Nothing repeats annotations or schema content.

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 low-complexity signature (1 param, no output schema), the description covers the trigger condition, the required token, the key return value (one mcp_upload_id per file), and the downstream handoff. The minor gap is the absent output schema: the exact return container shape and the criteria for choosing "the appropriate tool" are left unspecified, creating slight routing ambiguity. Annotations covering safety keep this close to complete.

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 100% and the schema already explains where the token comes from (upload_file request_hosted_upload: true). The description adds meaning the schema lacks: "the token covers all files they dropped on the page" clarifies that a single token maps to multiple files, which is essential semantic context for using the parameter correctly. This raises the score above the baseline.

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 opens with a specific verb+resource: "Fetch all files the user uploaded via the hosted upload page," naming both the action and the exact scope. It clearly differentiates itself from siblings by framing the tool as the retrieval step of an upload workflow, distinct from the add_* consumers it explicitly names.

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?

"Call this once after the user confirms they are done uploading" is an explicit trigger condition with a frequency hint ("once"). "Pass each to the appropriate tool (add_clips, add_article_media, etc.)" explicitly names the downstream alternatives, telling the agent what to do with the result and when to use those siblings instead.

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