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

Annotations declare only a mutation profile (readOnly=false, idempotent=false, destructive=false); the description adds substantial context beyond that: the 3 MB limit, non-idempotent duplicate behavior, immediate text indexing, the org-settings gating, and the returned citation syntax. 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?

One dense paragraph that front-loads the core action, then layers constraints and the sibling alternative. Nearly every sentence earns its place, though the prose is packed and could be broken into shorter units for faster scanning.

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 compensates by describing the return values (REF code, the referenceId used in [label](cite:<referenceId>)) and indexing behavior. Given six parameters and a mutation profile, this is complete enough for correct invocation.

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 already 100%, so the baseline is 3. The description still adds meaning beyond the schema by explaining that `title` defaults to the file name, that `number` is the reference's own designation, and that `content` is base64 with an optional data-URL prefix, clarifying parameter intent and defaults.

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 first sentence states a specific verb (upload) and resource (reference file to the document's project Reference Library), including the default side-effect of adding it to the document's references. It is clearly distinguishable from the sibling traceable_library_add_reference, which 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?

It names the alternative route (traceable_library_add_reference for files already in the library), warns that calling it twice files the file twice, states the 3 MB ceiling and tells the agent to upload larger files in the app, and notes the controlled-releases/admin prerequisite. Both when-to-use and when-not-to-use are covered.

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