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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the description doesn't need to repeat those. The description adds the directional asymmetry (BTC-source vs. token-into-BTC) and reveals that output includes venue counts, providing behavioral context beyond the annotations. It also frames the tool as a way to avoid trial-and-error discovery, which is useful. No contradiction with annotations.

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, front-loaded with the core function and the key limitation. It packs substantial context without redundancy. The second sentence could be slightly tighter, but overall it is efficient and well-ordered.

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 read-only coverage tool with an output schema, the description covers the essential logic, the directional restriction, and the practical motivation. The output schema presumably details the return structure, so the description doesn't need to. Rate limits are hinted at via the apiKey parameter. The only minor omission is explicit mention of error behavior, but the NO_LIQUIDITY reference gives some context. Overall, it is complete enough for an agent to use it correctly.

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 100%: both apiKey and chainId have descriptive text in the schema (apiKey for rate limit, chainId for destination chain). The description does not add any parameter-specific semantics beyond what the schema already provides, so the baseline of 3 applies.

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: it returns which tokens from ravn_tokens are reachable for BTC-native-source swaps on a given chain, including the number of venues per token. It distinguishes itself from ravn_tokens (which provides the full list) and the reverse swap direction. The title reinforces the scope, making the tool's role unambiguous.

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 scopes usage to BTC-as-source swaps and excludes the sell-into-BTC direction, stating it has 'nothing useful to say' there. It references ravn_tokens as the source list to filter, implying the alternative of using ravn_tokens for the full list. It also explains the practical use case: building a token list that will actually quote without hitting NO_LIQUIDITY errors, which tells the agent exactly when to invoke this tool.

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