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

With no annotations, the description carries the full burden and discloses important behavior: the URL is short-lived, reusable across multiple files until expiry, and requires an HTTP-capable client. It does not mention authentication scopes, error handling, or upload side effects, which keeps it from 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?

The description is front-loaded with the tool's purpose, then efficiently adds operational instructions in a logical order. Every sentence contributes necessary context for correct invocation, with no filler.

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 tool with no output schema, the description covers the return components (url, headers, filenameHeader) and the required follow-up workflow, which is enough to use it correctly. It still omits exact expiry duration and formal response shape, so it is strong but not fully exhaustive.

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%, so the schema already documents transactionId as the required UUID of the transaction to attach files to. The description adds only the general purpose of the parameter and no new syntax or format details, making the baseline 3 appropriate.

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 and resource: get a short-lived upload URL for attaching receipt/invoice files to a transaction. It also names accepted file types and the target entity, so an agent can identify exactly what this unique tool does.

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 explicitly explains when to use it and the critical constraint that file bytes cannot be sent through MCP. It then gives the required alternative workflow: POST raw file contents to the returned URL with the returned headers and the filename header. It also states the client prerequisite, leaving no ambiguity.

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