Stamp text on a PDF

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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the agent knows it writes without destroying. The description adds valuable context beyond annotations: it writes a new file, leaves the input untouched, and restricts free-tier use to the PAID and DRAFT presets in preset colours. This is strong transparency, though it omits overwrite and output details covered in the schema.

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 sentences, front-loaded with the core action and followed by write behavior and tier limits. Every sentence earns its place; 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?

The description covers the core action, the write-to-new-file behavior, input preservation, and free-tier limits, which is sufficient given 100% schema coverage for parameters. It does not explain the output/return or overwrite edge case, but with no output schema and overwrite documented in the schema, these are minor gaps.

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 the schema already defines all nine parameters, including text presets, colour, pages, opacity, position, font size, and overwrite. The description adds only a general reference to 'colour and position you choose' and repeats the free-tier preset constraint for text/colour, which is already in the schema. Baseline 3 is appropriate because the schema does the heavy lifting.

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 states a specific verb ('draw a word such as PAID or DRAFT across the pages') and resource (PDF pages), with concrete examples of the stamped text. It is clear what the tool does, though it does not explicitly distinguish itself from the sibling pdf_watermark_business, so sibling differentiation is missing.

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 only says 'Call this tool to draw a word...' but gives no when-to-use conditions, no when-not-to-use, and no alternatives (e.g., pdf_watermark_business). Usage is implied by the purpose, but explicit guidance is absent.

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