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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real behavioral context on top: data is QUARTERLY levels, it lags, the newest point is a quarter end and 'never today', and the response states the most recent observation date. That freshness expectation is exactly the kind of trait an agent cannot infer from annotations or schema.

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?

Three dense sentences with zero filler; the core purpose and ordering come first, the freshness caveat and optional window follow. Nothing repeats the title or the schema.

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?

For a read-only series fetch with an output schema, the description supplies enough: scope, ordering, lag caveat, and time-window controls. The only gap is the undocumented limit parameter, which an agent could easily get wrong.

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 description coverage is 0%, so the description must carry parameter meaning. It does cover since/until (with the YYYY-MM-DD format and narrowing behavior) and implies ticker, but the limit parameter (default 120) is never mentioned, leaving half the parameters undocumented anywhere.

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 names a specific verb+resource (a single macro series by ticker) and specifies scope and ordering (newest first), which cleanly separates it from the sibling search_macro_indicators, which implies multi-series lookup. An agent can pick the right tool without opening either schema.

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 tells the agent that since/until optionally narrow the window and that data is quarterly and lagged, which implies the appropriate context of use. However, it never states when to choose this tool over search_macro_indicators or what qualifies as a valid ticker, so the routing guidance is only implicit.

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