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

The description is rich in behavioral detail: it explains that no signature request, email, or quota use occurs (read-only), lists all possible issue types (PAGE_OUT_OF_RANGE, OFF_PAGE_RIGHT, etc.), describes the fallback behavior when anchor text is not found, and details the return structure (page dimensions, per-field validation, resolved coordinates). It also discloses auth requirements and error handling, all of which go beyond the annotations (readOnlyHint) to provide comprehensive transparency.

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?

The description is concise given the complexity: every sentence earns its place, starting with the core purpose, then behavioral guarantees, input equivalence, return structure, issue list, prerequisites, and auth. It is front-loaded and well-organized with no redundancy or filler. Despite its length, it is efficiently structured for an AI agent to parse.

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 only two parameters (both documented in schema), no output schema, and fully covered annotations, the description is exceptionally complete. It covers prerequisites (render status, auth), error conditions (410, missing key), return content (page sizes, field coordinates, issues), the full issue taxonomy, anchor resolution details, and the tool's relationship to create_signature_request. Nothing essential is omitted.

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?

The input schema has 100% coverage with descriptions, yet the description adds substantial value: it explains the equivalence to create_signature_request input, clarifies how anchor positioning works and the silent fallback behavior, describes the purpose of options and sourcePageWidth/Height, and details the semantic meaning of issues. This goes well beyond the schema's field-level descriptions.

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 explicitly states the tool validates field placement layouts against a render's page geometry before any signature request is created, email sent, or quota spent. It clearly distinguishes itself from create_signature_request by emphasizing that no request is created, and it lists the same accepted field types, making the purpose specific and well-differentiated from siblings.

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 description provides explicit guidance: use this tool before create_signature_request ('anything that previews clean will send'), explains the source render must have 'success' status, and what happens if the PDF ages out (410 error, fix by re-rendering). It also states that issues detected here do not cause create_signature_request to fail, reinforcing its role as a pre-validation step.

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