MCP Sample 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. The description only states what calculations it performs but doesn't disclose any behavioral traits like error handling (e.g., division by zero), precision, performance characteristics, or what the output looks like. For a tool with no annotation coverage, this leaves significant gaps in understanding how it behaves.

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 very concise - a single sentence in Japanese that efficiently states the purpose. It's front-loaded with the main function and includes parenthetical examples. There's no wasted text, though it could be slightly more structured if it included brief usage notes.

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 has no annotations and no output schema, the description is incomplete. While it states what calculations are performed, it doesn't cover important contextual aspects like return values, error conditions, or behavioral constraints. For a calculation tool with 3 parameters and no structured output information, the description should do more to help an agent understand how to use it effectively.

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 100%, meaning all parameters are documented in the schema. The description doesn't add any parameter semantics beyond what's already in the schema (operation with enum values, a and b as numbers). It doesn't explain parameter relationships, constraints, or examples. With high schema coverage, the baseline is 3 even without additional param info in the description.

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 what the tool does: '簡単な計算を実行します（加算、減算、乗算、除算）' translates to 'Performs simple calculations (addition, subtraction, multiplication, division).' This specifies the verb ('performs calculations') and the resource/scope ('simple calculations' with listed operations). It distinguishes from the sibling tool 'get_current_time' which is unrelated. However, it doesn't explicitly differentiate from potential calculation alternatives beyond listing 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 any prerequisites, constraints, or scenarios where this tool is appropriate versus other calculation methods. The only sibling tool 'get_current_time' is completely unrelated, so no comparison is needed, but the description offers no usage context at all.

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