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

With readOnlyHint=true and openWorldHint=true already present, the safety profile is clear. The description adds valuable cost transparency ('$0.005 per successful call via x402 (eip155:8453)'); 5 free calls/day across all tools', which is behavior beyond annotations. However, it does not disclose failure modes (e.g., invalid series, rate limits, authentication requirements), leaving some transparency gaps.

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 dense but fairly well-structured: it front-loads the core purpose and scope, then lists aliases and pricing. The list of example series could be seen as slightly excessive for conciseness, but it serves a practical purpose as a quick reference.

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 and rich annotations, the description is nearly complete: it explains what data is returned (latest, change, YoY, recent observations) and the cost model. It lacks explicit error handling or detailed behavior on invalid inputs, but for a read-only data retrieval tool, this is a minor gap.

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 schema fully documents all three parameters. The description lists example aliases but does not add any semantic details beyond what the schema already provides. Baseline 3 is appropriate when schema carries the full parameter burden.

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+resource: 'US macroeconomic time series from FRED' and then details the exact computed outputs (latest value, change vs previous and year-over-year, recent observations). It clearly distinguishes this tool from siblings like treasury_yields and fx_rates.

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?

Usage is implied by the description but there are no explicit when-to-use or when-not-to-use guidelines. It doesn't clarify, for example, when to choose this tool over treasury_yields or fx_rates, nor does it state that the tool is specifically for macro data rather than rates or currency pairs.

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