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

Annotations provide readOnlyHint=true, indicating this is a safe read operation. The description adds behavioral context by emphasizing performance optimization with jq_filter and noting the tool queries 'all' supported currencies, which clarifies scope. However, it doesn't disclose other traits like rate limits, authentication needs, or response format details. With annotations covering safety, the description adds some value but not rich behavioral context.

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 front-loaded with key guidance in the first two sentences, followed by the purpose statement. However, the inclusion of a JSON schema snippet in the description is redundant since there's no output schema in context signals, and it adds clutter. Overall, it's efficient but could be more streamlined by removing the schema duplication.

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 1 parameter with full schema coverage, readOnlyHint annotation, and no output schema, the description adequately covers the tool's purpose and parameter guidance. However, it lacks details on response format (e.g., what currencies are returned as strings) and doesn't differentiate from sibling tools, leaving gaps in contextual understanding for an agent.

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 input schema has 1 parameter with 100% description coverage, detailing jq_filter's purpose and examples. The description reinforces this by advising to 'always use' it for performance, adding usage context beyond the schema. However, it doesn't provide additional semantic details like specific filter examples for this tool's response. Baseline 3 is appropriate as the schema does heavy lifting.

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: 'query all the supported currencies on CoinGecko'. This is a specific verb ('query') and resource ('supported currencies'), though it doesn't explicitly differentiate from sibling tools like 'get_simple_price' or 'get_global' which might also involve currencies. The purpose is clear but lacks sibling differentiation.

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 explicit guidance on when to use the jq_filter parameter ('always use... to reduce response size and improve performance') and when to omit it ('Only omit if you're sure you don't need the data'). However, it doesn't mention when to use this tool versus alternative currency-related tools in the sibling list, such as 'get_simple_price' or 'get_coins_markets'. The guidance is clear for parameter usage but lacks tool-level context.

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