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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true. The description adds valuable context: the source of evidence (settled observations), the exclusion of non-settled data, determinism, and evidence-bounded nature. It does not contradict annotations and enhances transparency.

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 extremely concise, three short clauses, no fluff. It front-loads the core action and constraints. Every word 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?

Given zero parameters and a simple output (price bands), the description covers the essential input constraints. The '0.005 USDC' is cryptic and might need clarification, and the output schema exists but is not shown, so the description needn't detail return values. Minor ambiguity costs a point.

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?

There are zero parameters and the schema is fully open (additionalProperties: true), so the description doesn't need to explain parameters. The mention of '0.005 USDC' might hint at pricing or stake but is ambiguous, which is a minor gap.

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 states a specific verb ('derive') and resource ('price bands') and adds constraints ('settled observations, never traffic or unsigned quotes'). However, it doesn't differentiate from siblings like quote_freshness_guard or market_data_snapshot, which could be related.

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 implies usage: when you need price bands from settled data. But it doesn't explicitly state when not to use it or mention alternatives. With 100+ siblings, more explicit routing would help.

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