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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds useful context that the data is a public, verifiable ledger for any account, but it doesn't say whether the aggregates are all-time or constrained by limit, nor anything about volume or response shape.

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?

Two dense sentences that front-load the core purpose and then the access condition; nothing is wasted. The closing clause 'the same ledger is public' is slightly redundant with 'The public, verifiable ledger' that opens 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?

With no output schema, the description does the essential work of enumerating returned fields (counts, win rate, mean return, recent closed rows). The notable gap is whether the aggregates are all-time or scoped to the limit window — an ambiguity that matters for correct interpretation of results.

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 both parameters (book enum, limit with default 20 and max 500) are fully documented in the schema. The description reinforces 'for a book' and 'most recent closed rows' but adds no syntax or default information beyond the schema, so baseline 3 applies.

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?

Concretely states the resource and payload: counts, win rate, mean return for a book, plus the most recent closed rows. It's clear this is the public/historical ledger view rather than a live-picks view, distinguishing it implicitly from picks_open/picks_today. It stops short of naming a sibling explicitly, so the differentiation stays inferential.

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 line 'Answers any account, free included; the same ledger is public' gives an access/usage condition, and 'most recent closed rows' hints at the historical use case. But it never states when to choose this over picks_closed or books_mine, and no exclusion is given, so 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.