Read the text of a PDF

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

Annotations already cover read-only, idempotent, non-destructive and closed-world, but the description adds genuinely new behavioral context: scans yield nothing, custom-encoded fonts yield glyph indices, and the tool reports which case occurred. It also discloses a 'Free tier: unlimited' cost/quota trait the annotations do not 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?

Four short sentences, front-loaded with the core purpose and the failure modes immediately after; nothing is padded. The 'Read-only' clause is mildly redundant with readOnlyHint=true, which keeps it from a 5.

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 explain the two degraded outcomes and that the tool signals which applies. It does not describe the shape of a normal successful return (e.g., plain concatenated text vs. per-page), leaving a modest gap for a read 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% with only two simple parameters (path, pages) fully documented in the schema, including the page-range syntax. The description adds no additional parameter meaning, so the 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?

States a specific verb and resource ('best-effort text extraction from standard-font PDFs'), and the scoping to standard-font PDFs separates it from generic PDF siblings such as pdf_info, pdf_pages, and pdf_merge. An agent can select it over those without opening any schema.

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?

Gives a clear usage condition ('for best-effort text extraction from standard-font PDFs') and effectively rules out scanned documents ('Returns nothing for a scan (no OCR)'), which functions as a when-not-to-use signal. It stops short of naming an alternative tool (e.g., for OCR or metadata), so it is not a full routing directive.

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