pdf_text

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

Goes well beyond the readOnly/idempotent annotations: it discloses the dual extraction backend (PDFium vs built-in) and that the output reports which was used, warns about invisible/white-on-white/tiny/off-page text, and explicitly frames extracted text as data rather than instructions — a real prompt-injection safeguard.

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 tight sentences, front-loaded with the core action, then inputs, then backend behavior, then the safety note. No filler and nothing buried.

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 carries the return-value burden and does so partially — it says output is page-by-page, reports which extractor ran, and includes hidden-text warnings. It stops short of describing the exact response shape (e.g. how pages are delimited, truncation signaling for max_chars).

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 coverage is 100%, so all five parameters are already documented, including the page-range syntax and the 8 MiB limits. The description restates the page-range example and the three source modes but adds no syntax or constraint detail beyond the schema, so baseline 3 applies.

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?

Opens with a specific verb+resource: 'Extract the text of a PDF, page by page.' That is clearly distinct from pdf_info, pdf_render_page and pdf_search, though the description never names those siblings to reinforce the distinction.

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 explains the input modes and the optional page range, which implies when the tool applies, but it never states when to prefer pdf_search or pdf_info over this, nor any exclusions. Usage is implied rather than guided.

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