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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. But the description adds nothing about the three divergent split behaviors, whether the original file is preserved, or any size/limits context beyond what the schema states — a real gap for a tool whose mode fundamentally changes the output.

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 sentences, front-loaded with the action and resource. The trailing 'Accepts pdf. Returns the result file.' is largely redundant with the schema and annotations, keeping it short of 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?

The tool has a nested options object with three distinct behavioral modes, no output schema, and no explanation of what the returned file contains. The description does not address any of this complexity, leaving an agent unable to predict what a given mode will produce.

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 the file/upload_id/content_base64 parameters are well documented and the baseline is 3. The description adds nothing, though, and the 'mode' enum values (ranges/extract/each) and 'pages' format carry no schema descriptions, so it misses a chance to compensate where the schema is weakest.

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 ('Split a PDF into parts or extract pages') that an agent can distinguish from merge-pdf and delete-pdf-pages at a glance. However, it never names an alternative or clarifies overlap with delete-pdf-pages/reorder-pdf, so sibling differentiation is only implied.

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?

No indication of when to use this versus delete-pdf-pages, merge-pdf, or reorder-pdf, and no guidance on choosing between the 'ranges', 'extract', and 'each' modes. The agent is left to infer all selection logic from the schema defaults alone.

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