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

Annotations already declare non-read-only, idempotent, non-destructive, but the description adds the concrete idempotency semantics (first acceptance wins, repeats return `already_accepted`), the authorization profile (owner only, `write` required), the consent-revocation failure mode, and the $0 cost. These are behavioral facts an agent cannot infer from the 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?

Front-loaded with the core action, then edge cases and auth in descending priority; parentheticals carry error codes and defaults without padding. Every clause contributes a constraint, failure code, or scope fact; the trailing 'Requires `write`. $0.' is terse and load-bearing.

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 still covers authorization, idempotency, consent failure, and permission scoping, which is most of what an agent needs. It does not say what the call returns or what visible state change follows acceptance (e.g., whether the asset becomes usable immediately), a small remaining gap.

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 67%, and the description adds real meaning to `permission_scope` beyond the enum documentation: `piece` is the default and `author` applies only when the link asked for it, plus the consent precondition. `asset_id` is already documented in the schema and `project_id` remains undescribed in both places, which keeps this short of a 5.

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?

States a specific verb and resource (accepts a contributed file) and pins down the origin precisely: a file a third party sent through a guest upload link, so the piece can use it. That framing implicitly separates it from owner-upload paths handled by siblings like complete_upload, and the `not_a_contribution` note makes the boundary explicit.

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?

Covers when to use it (guest-contributed file for this piece) and when not to: an owner-uploaded file needs none (`not_a_contribution`), a guest who withdrew consent cannot be accepted, and repeat calls are no-ops (`already_accepted`). It also states the actor constraint (only the piece's owner) and the required `write` scope.

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