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

With no annotations, the description carries the burden of disclosing behavior. It does reveal the key output fields and interpretation layer, which is useful, but it leaves important behavioral details vague—such as what 'ranked actions array' contains and how 'recession_imminent detection' is determined. It does not mention side effects, data source, or caveats, though this likely a read-only data tool.

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 a single, dense sentence that packs all core information—the resource, the interpretation layer, and the main outputs—without wasted words. It is efficiently structured and easy to parse.

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?

In the absence of an output schema and annotations, the description outlines the main return fields, but it is not fully complete. Terms like 'ranked actions array' and the specifics of 'un-inversion pattern' are undefined, leaving the agent with an incomplete picture of what the tool returns. For a zero-parameter tool, this is adequate but not rich enough for a higher score.

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 details. The description is not required to explain parameters. The baseline of 4 applies because there is nothing to document and no ambiguity about invocation inputs.

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 identifies the resource as 'Treasury 10Y-2Y spread' and adds an 'interpretation layer' with specific outputs (curve_state, days_inverted_last_365, recession_imminent, ranked actions array). However, it lacks a direct verb and does not explicitly differentiate from siblings like yield_curve or yield_curve_v3, so it falls short of a 5.

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?

No guidance is provided on when to use this tool versus alternatives such as yield_curve or yield_curve_v3. There is no mention of exclusions, prerequisites, or preferred scenarios, making the description purely positional rather than instructive about tool selection.

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