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

Annotations already declare non-readonly, non-destructive, idempotent, open-world. The description adds genuinely new behavior: original layout/fonts and untouched content are preserved, up to 3 before/after page previews are returned, and the server uploads local paths for you. It still does not mention permissions, size limits, or what happens with multiple failing edits in a batch.

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?

Front-loaded with the verb and resource, then capabilities, then option-level guidance. Every sentence carries content, though the second sentence packs a dense `op`, `scope`, `match`, `fit` enumeration that is somewhat run-on.

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?

For a nested-schema mutation tool with no output schema, the description covers the core edit model, targeting rules, and the preview return. Gaps remain around the many `options` flags and password handling, but the schema's 80% coverage plus defaults mitigate much of that.

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 80%, so the baseline is 3 and most fields are already documented. The description does add real meaning beyond the schema for scope.pages, scope.after/occurrence disambiguation, and the preview payload, but leaves the large `options` surface (atomic, dry_run, strict, ocr, tidy) entirely unexplained.

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 with enumerated capabilities: 'Edit the text of an existing PDF in place: replace, delete, redact, insert, or fill form fields.' This is far more specific than the title, but it never names or contrasts with siblings such as pdf_batch or pdf_find, so an agent must infer the boundary on its own.

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 clear in-tool routing rules: scope.pages for a single page, scope.after/occurrence to disambiguate identical matches, and op:'redact' when the text must be unrecoverable. It does not say when to prefer pdf_batch (many files) or pdf_find (locating text first), so cross-tool selection is left implicit.

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