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

Annotations only supply destructiveHint=true, so the description carries most of the behavioral burden. It usefully discloses that the URL is one-time and that the GraphQL mutation is generateEtchSignURL returning { url }, partly explaining why the operation is flagged destructive, but it does not say what the URL invalidates, whether prior URLs are revoked, or any auth requirements.

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 short, front-loaded clauses: purpose and scope first, then use case, then the GraphQL mutation name and return shape. Every sentence earns its place 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?

With no output schema, the description compensates by stating the return value ({ url }), and the mutation name aids debugging. The two required params are fully covered by the schema, though the description does not note the fragility of a one-time link.

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%, so both parameters (signer_eid, client_user_id) are already documented with their source and purpose. The description adds no parameter-level detail beyond the schema, which is the baseline-3 case.

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 ('Generate a one-time embedded signing URL') scoped to 'a specific signer in an Etch packet', which separates it from siblings like anvil_get_etch_packet and anvil_create_etch_packet. The parenthetical use case (iframe/redirect signing flows) further pins down the intent.

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?

The parenthetical '(for iframe/redirect signing flows)' gives an implied context for use, but the description never states when to use this instead of getting the packet or creating one, nor any prerequisites. Usage is inferable rather than explicit.

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