Read PDF text

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

Annotations only declare readOnlyHint=true and openWorldHint=false, but the description goes further: it discloses that the tool actively *refuses* on scan-only PDFs, describes the return shape (1-based page numbers, headings prefixed with '# '), and notes pages are paged via from/to. That is behavioral context the annotations cannot carry.

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 paragraphs, front-loaded with the core behavior, then the scan caveat, then the fallback path. Every sentence carries information an agent needs; nothing is padded.

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?

There is no output schema, yet the description itself explains the return format (pages with text, heading markers, page numbering) and the failure mode. Combined with 100% schema coverage for inputs, an agent has everything required to call and interpret this tool.

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 from/to/mode/max_chars are already documented in the schema — baseline 3 applies. The description only restates pagination via from/to and implies the paragraph mode; it adds no format, bounds, or budget guidance beyond the schema.

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 and resource ('Read the text of a PDF, page by page') and immediately scopes what it returns (paragraph-reconstructed text with 1-based page numbers). It also carves out its niche against siblings by distinguishing text-layer PDFs from scans that require pdf_render_page.

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?

Explicitly states when the tool works (PDFs with a text layer), when it does not (scanned PDFs, i.e. pdf_info reports scanned: true), and what to do instead — render with pdf_render_page or locate the chapter via pdf_outline first. This is a near-complete decision tree for the caller.

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