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

Goes well beyond the read-only/idempotent annotations: it specifies the two accepted auth header formats, that calls consume the key's daily quota, the edition freshness model, and the as_of quoting caveat. This is exactly the operational context annotations can't express.

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?

Front-loaded with purpose and payload, then auth and cost. Dense but nearly every clause carries information; the closing 'not investment advice' is the one piece of boilerplate, though it is arguably relevant for market data.

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?

With no output schema, the description still conveys the return contents and the difference between the two response formats, plus auth, quota, and freshness requirements. Nothing an agent needs to invoke it correctly is missing.

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% and the enum description already defines text vs json, so the baseline is 3. The description adds a cost dimension ('cheapest') and restates the payload shape per format, giving marginal value beyond the schema.

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?

States a specific verb and resource ('Latest MacroTape market brief') and enumerates the exact contents: Treasury par curve, spreads, curve shape, ECB currencies vs USD, top movers, dollar breadth. 'Newest weekday AM/PM edition' implicitly separates it from get_brief_by_date, so an agent can route without opening the 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?

Gives clear selection signals: use this for the newest edition, and format=text is the 'cheapest' option while json is the full brief. It does not explicitly name alternatives like get_brief_by_date or get_sample and when to prefer them, so it falls short of full when/when-not routing.

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