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

The description asserts the operation is 'idempotent for the same owner', while the annotations declare idempotentHint=false, a direct conflict about repeat-call behavior. Valuable context is present (no new charge, session + private proof required, ownership cannot be transferred), but the explicit contradiction with the structured hint makes the behavioral signal untrustworthy.

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?

Four short sentences that front-load the core action and the no-charge guarantee before prerequisites and ownership rules. Slight redundancy between the 'global right' and 'another owner cannot claim it' clauses, but nothing is padded.

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 must carry the outcome burden, and it does explain the resulting state (account records the global right, subsequent access via the code) plus prerequisites. It falls short on error conditions and conflicts with the idempotency hint, leaving an agent unsure about retry behavior.

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 both parameters are already documented, giving a baseline of 3. The description adds conceptual meaning ('private proof of the purchase', a cookie also being accepted, the code continuing to open the document itself) but no syntax or format detail beyond the schema.

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 gives a specific verb ('Links') and a precise resource/relationship ('anonymous purchase to the authenticated account') plus a cost guarantee ('without a new charge'). An agent can distinguish this from nearby tools such as documento_acesso, get_document, or claim_guest_tracking, though no sibling is named explicitly.

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?

Usage is implied rather than stated: 'Requires a session and private proof of the purchase' establishes prerequisites and the anonymous-purchase context. However, it never says when to prefer this over alternatives like claim_guest_tracking or documento_acesso, nor what to do if the proof is missing.

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