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

Annotations already cover idempotency and non-destructiveness, so the description's additional recovery semantics are valuable: pages are retained only if still parseable, and a clean output file is produced. This adds behavioral context beyond the structured annotations and does not contradict 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 a single sentence with no filler, front-loading the key scope ('every page that can still be parsed') and the outcome ('writing a clean file'). Every phrase earns its place.

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 one-parameter repair tool with no output schema, the description states the input use case and the produced artifact. File-supply details are already covered by the schema, so nothing essential for invoking the tool is missing.

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 single file parameter is fully documented in the input schema, including url, base64, and filename with descriptions, giving 100% schema coverage. The description adds no parameter-specific detail, which is acceptable at the baseline.

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 uses the specific verb 'Rebuild' with the resource 'corrupt or unreadable PDF' and states the expected outcome: recovering parseable pages and writing a clean file. This clearly distinguishes repair_pdf from siblings like compress_pdf or split_pdf, which address different PDF operations.

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 gives clear usage context: use it when a PDF is corrupt or unreadable. It does not explicitly name sibling alternatives or state when not to use it, so it falls short of a 5 but is still effective.

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