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

Annotations only say openWorldHint=false and destructiveHint=false, so the description carries most of the burden and does so well. It discloses that the service resolves storage location and content hash server-side, that signing links are emailed to counterparties (a real external side effect), and that no tokens are returned. These are exactly the behavioral facts 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?

Four sentences, each earning its place: purpose first, then document sourcing constraint, then signer configuration, then delivery semantics. Nothing is padded or restated from the schema.

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?

The tool is reasonably complex (nested signers array, large required envelope object), but an output schema exists so return shape needs no explanation, and the description covers the decisions an agent must actually make. The gaps are the required envelope object's fields and reminderIntervalDays, neither of which the description touches.

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 only 29%, so the description must compensate, and it does for the highest-risk parameters: document sourcing (sourceCompanyId/sourceDocumentId vs the explicitly forbidden S3 bucket/key) and the signers array's role and signingOrder conventions with concrete enum values. It leaves the many nested envelope.* fields (id, status, provider, userId, hashes) and reminderIntervalDays unexplained in prose; the envelope object in particular is required yet undocumented.

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 opens with a concrete verb and resource: 'Open a multi-signer signature envelope over an existing company document.' That distinguishes it from generic document tools (documents_create_document) and from the read-side siblings (signature_get_signature_envelope). It does not explicitly name a sibling alternative, which is why it stops short of a 5.

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 actionable invocation guidance: resolve the document via source_company_id + source_document_id and explicitly 'do not supply document_s3_bucket/document_s3_key.' It also prescribes signer roles and ordering. There is no when-not-to-use guidance or named alternative tool for, e.g., single-signer or non-company-document flows.

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