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

With no annotations provided, the description takes full burden and delivers well. It discloses the payment requirement ($0.05 via x402), free units for new wallets, the return structure (reason-code index, distributions, cross-tool concentration), and the neutral nature of the aggregation. This is valuable behavioral context beyond a simple read operation.

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 slightly long due to the payment details and URL, but the content is front-loaded with the purpose ('NEUTRAL AGGREGATION') and each piece of information is necessary for correct invocation. It could be tighter, but all sentences are functional.

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 no output schema, the description thoroughly explains what the tool returns (reason-code index, distributions of signal_strength/risk_band/staleness_tier, cross-tool concentration) and what it aggregates. For a parameterless tool, this is complete enough for an agent to understand the tool's role and expected output.

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 tool has zero parameters, so the schema provides no parameter semantics. The description appropriately does not add parameter details since there are none; instead, it focuses on payment and output structure, which is the only context needed. This is a baseline of 4 for zero-parameter tools.

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 verb as 'aggregation' and specifies the exact input resources (fed_rates_v3, inflation_v3, yield_curve_v3) and output contents (reason-code index, distributions, cross-tool concentration). It also distinguishes from siblings by noting 'No directional labels, no alignment score, no venue hints' and framing itself as a one-call aggregator.

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?

It explicitly says 'One call replaces three for macro-aware agents', which clarifies when to use it: when you need a neutral aggregate of those three tools. It also lists what it does NOT provide (directional labels, alignment score, venue hints), helping agents avoid using it for those purposes, though it doesn't explicitly name alternative tools for those cases.

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