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

Annotations only cover the safety profile (readOnly, non-destructive, openWorld); the description adds substantive behavioral facts beyond them — the 30 KB inline ceiling, that no document processing occurs, that it is normally not billed, and the underlying HTTP route. These are exactly the constraints an agent needs before calling.

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 with zero filler; the core action and the size constraint are front-loaded, and the billing/endpoint notes come last as secondary detail.

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 carries the return-value burden and does so by specifying base64 plus the 30 KB limit that determines when that return is actually usable. Combined with the inherited safety annotations, nothing essential 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?

Schema description coverage is 100% and there is a single required file_id parameter, so the schema already does the work. The description reiterates file_id and the base64 return but adds no format or sourcing detail beyond the schema, which is the expected 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 names a specific verb and resource ('Fetch a stored file by file_id'), states the return format ('as base64'), and is clearly distinguishable from siblings like dochorizon_upload_file and the capture_* tools. An agent knows exactly what this tool produces 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 conditional: files up to 30 KB are returned inline, and for larger files the agent should pass file_id to other tools instead. It also clarifies this is not a document-processing tool. It stops short of naming the specific sibling tool to use for large files, so the routing is implied rather than explicit.

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