MCP Document Reader

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

No annotations are provided, so the description carries full burden. It mentions the tool extracts images and returns JSON metadata, but lacks critical behavioral details: whether it modifies the original file, handles errors (e.g., invalid paths), requires specific permissions, or has performance constraints. For a file operation tool with zero annotation coverage, this is a significant gap.

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 appropriately sized with three sentences: purpose, parameters, and return value. It's front-loaded with the core functionality. The parameter and return explanations are necessary given the lack of schema descriptions, though the structure could be slightly more polished (e.g., avoiding markdown-like syntax).

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 (file processing with two parameters), no annotations, and an output schema present (which handles return values), the description is minimally adequate. It covers purpose and parameters but lacks behavioral context like error handling or side effects. With output schema reducing the need to explain returns, a score of 3 reflects this partial completeness.

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 0%, so the description must compensate. It explicitly documents both parameters: 'filename' as the path to the DOCX document and 'output_dir' as an optional directory for saving images. This adds clear meaning beyond the schema's generic titles. However, it doesn't detail parameter formats (e.g., absolute vs. relative paths) or constraints.

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 ('Extracts embedded images'), target resource ('from a DOCX file'), and output format ('returns structured JSON metadata'). It distinguishes itself from sibling tools like read_document, write_presentation, and write_word_document by focusing on image extraction rather than document reading or writing 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 provides no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., file must exist, DOCX format required), compare with similar tools, or indicate scenarios where extraction might fail. The agent must infer usage from the purpose alone.

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