MCP PDF Reader

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

No annotations are provided, so the description carries the full burden. It mentions the extraction action but doesn't disclose behavioral traits such as what format the extracted image is in (e.g., PNG, JPEG), where it's saved, error handling for invalid indices, or performance implications. The description adds some context (dependency on list_pdf_images) but lacks details on output or side effects.

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, efficient sentence that front-loads the purpose and usage guidance without any wasted words. Every part of the sentence serves a clear function, making it easy to parse and understand quickly.

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?

Given the tool's moderate complexity (extraction operation with 2 parameters), no annotations, and no output schema, the description is incomplete. It explains the input dependency but doesn't cover output format, error cases, or side effects. However, it provides enough to use the tool minimally, aligning with a baseline adequacy score.

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 schema already documents both parameters (filePath and imageIndex) with clear descriptions. The description adds minimal value beyond the schema by implying the imageIndex is 0-based and from list_pdf_images, but this is redundant with the schema's description. Baseline 3 is appropriate as the schema does the heavy lifting.

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 clearly states the specific action ('extract a specific image from a PDF') and resource ('PDF'), distinguishing it from sibling tools like list_pdf_images (which lists images) or read_pdf (which reads text). It explicitly mentions using list_pdf_images to get indices, which helps differentiate its purpose.

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 explicitly states when to use this tool ('by its index') and provides a clear alternative ('use list_pdf_images to get available indices'), guiding the agent on prerequisites and distinguishing it from other PDF-related tools. This eliminates ambiguity about how to obtain the necessary input.

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