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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the agent knows it's a safe, non-destructive query. The description adds value by revealing behavioral details: it returns ALL three stablecoins ranked, includes a recommendation for EUR destinations, and specifies that the output includes a settleBody ready for a POST to /settle. This goes beyond annotations without contradiction.

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 three sentences with zero waste. The first sentence defines the tool's domain and inputs. The second provides a specific, actionable recommendation. The third explains the output structure and next-action step. Every sentence earns its place, and the most critical information (what the tool does, key recommendation) is front-loaded.

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's moderate complexity (3 required parameters, no enums, no nested objects), the description is largely complete. An output schema exists, so return value details are not the description's job. The description covers inputs, algorithm (ranking, EURC recommendation), and output format (settleBody). A minor gap: it doesn't specify what 'settlement efficiency' means or the ranking criteria, but the output schema and sibling tool design likely handle that.

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 coverage is 100%, so the baseline is 3. The description adds some meaning by explaining the relationship between parameters (e.g., 'from' is source currency, 'to' is destination currency) and how they determine the algorithm (EUR destination triggers EURC recommendation). However, it doesn't add constraints or format details beyond the schema's basic descriptions.

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: multi-stablecoin settlement routing. It specifies the verb ('returns'), the resource ('stablecoin options'), and the core function ('ranked by settlement efficiency'). This distinguishes it from sibling tools like settlement.nl (natural language settlement search) and stability.stablecoin_route (stability-focused routing), as it returns concrete settlement data with a POST-ready payload.

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 clear context for when to use this tool: given amount, source currency, and destination currency. It explicitly recommends EURC for EUR destinations to avoid cross-currency conversion. However, it does not explicitly state when NOT to use it (e.g., for speculative routing or non-settlement queries) or mention alternatives among siblings like stability.stablecoin_route.

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