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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description still adds real value by disclosing the paid x402 pricing model, the $0.50 per-call cap, and that the call returns payment requirements plus a URL. It does not say what an unpaid call looks like or how the 402 challenge must be satisfied.

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 the price and resource, then use cases, then return shape and a sample link — a sensible ordering. The parenthetical pricing is slightly dense but every clause carries information.

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 carries the burden and does so: it names the fields each brief contains, states that the response is x402 payment requirements plus a URL, and points to a free sample. The only missing piece for a fully self-sufficient definition is the default for the optional `to` parameter.

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 0%, so the description must compensate; it supplies the YYYY-MM-DD format and the important 'up to 366 days' range constraint that the schema does not express. It leaves one gap: `to` is optional but the description never states the default behavior when it is omitted.

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 resource and scope: archived twice-daily briefs retrieved over a date range. The word 'archived' implicitly distinguishes it from get_latest_brief, and the enumerated content (sentiment, funding, open interest, prices, news, macro calendar) makes the resource concrete.

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 use cases ('backtesting, reviewing how the market narrative evolved, or filling a report gap'), which grounds when to reach for it. It stops short of explicitly naming get_latest_brief as the alternative for current data, so the sibling routing is left to inference.

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