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

The annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is clear. The description adds value by disclosing the return shape ({ operation, where, how }) and the behavior for unrecognized operations (a note explaining the plane boundary rather than an error), which goes beyond what the annotations alone provide.

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 fluff. It front-loads the main purpose, then immediately provides the return shape and the key alternative. Every sentence earns its place.

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 single-parameter lookup tool with no output schema, the description is complete: it explains what the tool does, what it returns, what happens for unknown input, and when to use a sibling tool instead. No critical information for correct invocation is missing.

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 already covers the single parameter completely, including a description, examples, and the unknown-name behavior. The description does not add meaningful parameter semantics beyond reinforcing the use case, so the baseline of 3 is appropriate given 100% schema coverage.

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 defines a specific verb–resource pair: 'look up how to perform one crypto-plane operation locally'. It also states the exact use case—when the expected tool is not on this server—and explicitly distinguishes this from setup_local_crypto, making the tool's unique role clear.

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 tells the agent when to use this tool ('the targeted answer for "the tool I expected is not on this server"') and names the alternative with its condition ('Use setup_local_crypto instead when you need the whole local setup rather than one command'). This gives explicit routing guidance with no need for inference.

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