Custom PDF MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions that the directory path must be absolute, which adds some context, but it does not cover critical behaviors such as error handling (e.g., if the path is invalid), permissions needed, whether it recursively searches subdirectories, or the format of the returned dictionary. For a tool with no annotations, this leaves significant gaps in understanding its behavior.

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 concise and well-structured, with a clear purpose statement followed by 'Args' and 'Returns' sections. Each sentence serves a purpose: stating the tool's function, explaining the parameter, and describing the return value. It avoids unnecessary details, making it efficient and easy to parse.

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 low complexity (one parameter, no annotations, no output schema), the description is minimally adequate. It covers the basic purpose and parameter requirement but lacks details on behavior, error handling, and output structure. Without annotations or an output schema, the description should provide more context about what the returned dictionary contains and how the tool behaves in edge cases.

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 description adds meaningful semantics for the single parameter 'directory_path' by specifying it must be an absolute path, which is not covered in the input schema (0% schema description coverage). This compensates well for the lack of schema details, providing essential guidance for correct usage. With only one parameter, the description effectively clarifies its purpose beyond the schema.

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 tool's purpose: '列出指定目录下的所有PDF文件' (List all PDF files in the specified directory). It specifies the verb (list) and resource (PDF files in a directory), making the action clear. However, it does not explicitly differentiate from sibling tools like 'get_pdf_info' or 'read_pdf_text', which focus on individual PDFs rather than listing them.

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 does not mention sibling tools or contexts where listing PDFs is preferred over other operations. The only usage hint is the parameter requirement, which is insufficient for distinguishing from other tools.

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