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

The description discloses key behavioral traits beyond the annotations: the exact bytes are printed, normalization to PDF, free/no payment, 30 MB upload limit, US Letter output, literal handling of {{...}}, and the reserved address zone behavior (content pushed down or blank page prepended). It even explains resulting page-count increases. Annotations only state readOnlyHint=false and openWorldHint=true, but the description adds rich operational context without contradicting them.

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 long but every sentence earns its place. It is front-loaded with the core purpose, then logically covers usage guidance, delivery methods, size limits, literal handling, and the address zone effect. Paragraphs are well-separated, and the content is dense with no filler or repetition of schema definitions.

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?

Despite having no output schema, the description enumerates the return values: 'documentId, the stored page count, byte size, and source format.' It also addresses edge cases like literal {{...}} handling, page-count inflation, and per-format details referenced via postagent://formats. Given the tool's complexity and the lack of an output schema, the description is remarkably complete.

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 schema already provides 100% coverage for each parameter, so the baseline is 3. The description adds meaningful cross-parameter semantics: it explicitly states that exactly one of content, contentBase64, or url must be supplied, and that none or multiple is an error. It also clarifies format inference and the default for inline content. This goes beyond the per-parameter schema descriptions and adds useful constraint clarity.

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 specific verb+resource: 'Upload and normalize a FINISHED, ready-to-mail document to PDF.' It clearly distinguishes itself from the sibling create_template by stating 'identical content, no mail merge' and explicitly naming the alternative. This unambiguously communicates what the tool does and how it differs from related tools.

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 when-to-use guidance: 'Choose this when the content is final and IDENTICAL for every recipient.' It also gives a concrete alternative: 'Use create_template instead only when the content must vary per recipient via {{fields}}.' It further clarifies the bulk-mailing scenario and the free/no-payment aspect, leaving no ambiguity about when this tool is appropriate.

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