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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the description's job is to add beyond that. It does contribute a hard row cap and a history start date (October 3, 2026) plus the warning that coverage varies, but it never says whether hitting 100 rows means truncation or sampling, which matters for a bounded read.

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 with no filler; the subject and row cap are front-loaded and the cross-reference comes last where a reader needs it.

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?

There is no output schema, so the description is the only source of shape information, yet 'observations' is never unpacked into what fields come back. Combined with two undocumented parameters and unspecified truncation behavior at the 100-row cap, it is adequate but not complete.

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 only 33%, so the description must carry the undocumented majority. It clarifies that the day is an exported UTC day and defers range discovery to days_available, but leaves 'wallet' (format, single vs list) and 'api_key' entirely unaddressed.

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?

Names the resource precisely ('Wallet and walletcoin daily observations') and adds a scope constraint (at most 100 rows) plus a date floor. It does not explicitly contrast with close siblings like day_full_stats, but the row cap and per-wallet focus give an agent enough to distinguish it.

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?

The final sentence routes the agent to days_available to discover the valid UTC day range, which is genuine usage guidance. However, there is no statement of when to prefer this over day_full_stats or coin_trades, so the choice among aggregate-style siblings 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.