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

With no annotations, the description carries the burden of behavioral transparency. It discloses the primary behaviors (resolving to a URL and confirming existence), but does not explain failure behavior (e.g., what happens if the URN doesn't exist), return format details, or any side effects. This adds some value beyond the name but lacks depth.

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 two sentences with no redundancy. It front-loads the core action and example, then adds a usage hint. Every word contributes, making it highly efficient and well-structured.

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 simple one-parameter tool, the description covers the essential purpose and provides an example. However, the lack of an output schema and no mention of return format or error handling leaves the agent uncertain about the response structure. While not overly complex, the description could be more complete.

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 schema description coverage is 0%, so the description must compensate. It provides a concrete example (fojin:cbeta/T0001.1) that illustrates the expected URN format, adding meaning beyond the schema's bare type definition. However, it does not fully explain variations or constraints, leaving room for ambiguity.

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 function: resolving a fojin URN to a reader URL and confirming existence. It uses a specific verb ('resolve') and resource ('fojin URN'), provides a concrete example, and distinguishes itself from sibling tools by focusing on URN resolution rather than searching, reading, or verifying quotes.

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 says 'Use to verify or dereference a citation,' giving clear context for when to use it. It does not explicitly list exclusions or alternatives, but the guidance is sufficient to indicate appropriate use cases without confusing it with sibling tools.

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