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

Annotations already declare a safe read (readOnlyHint=true) with no open-world access, and the description adds meaningful context beyond that: the three-month data lag, the automatic fallback to the latest delayed day, and the refusal rule for out-of-range dates. It does not describe the response shape, but that is minor for a read 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?

Three short sentences, front-loaded with what the score is and its range before the default and the refusal rule. The default-value clause duplicates the schema description slightly, but the repetition is cheap and reinforces the most likely agent question.

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 one-optional-parameter read tool with no output schema, the description covers scale, staleness, default, and error conditions — enough to call it correctly. Only the explicit pointer to the live-score sibling 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%, so the YYYY-MM-DD format and optionality are already documented. The description nonetheless adds value by restating the default and, more importantly, disclosing the validation boundary beyond which a date is refused — information the schema does not carry.

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 resource (BTC Intel Score), its scale (0 to 100), and its scope (delayed, three months behind the live record, as the public site shows it). This implicitly separates it from get_live_score, though it never names that sibling outright.

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 states the default behavior clearly ('Without a date: the latest delayed day') and gives an explicit exclusion ('A date after the Delayed date is refused'). What it omits is direct routing to get_live_score for current data, so an agent must infer the alternative.

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