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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description usefully adds the payload's shape (per-exchange balances, 24h/7d net flows, warning flags) and the default all-exchange scope, but says nothing about data freshness, update cadence, or whether 'paused withdrawals' style flags are historical or current.

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 sentences, with the data scope front-loaded and the default-scope instruction appended. The opening clause is a bit padded and the field list is dense, but nothing is redundant and no sentence is wasted.

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-only tool with annotations but no output schema, the description carries the return-value burden well by naming the metrics returned. The main remaining gap is that it does not state the response structure (one record per exchange vs. a single aggregate), which an agent would need for downstream shaping.

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 single optional 'exchange' parameter is already documented with examples. The description goes slightly beyond the schema by specifying the omit-behavior ('leave exchange out for every covered exchange'), clarifying the default aggregate scope rather than repeating 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?

The description names the resource (proof-of-reserves exchange reserves) and enumerates the data it covers: bitcoin/ether/stablecoin balances, 24h and 7d net flows, and flags like unusual outflows or paused withdrawals. That is enough to tell it apart from siblings such as get_etf_flows or get_asset_metrics, though the leading clause ('Coins CryptoKeyhole can see on chain') is roundabout rather than a crisp verb+resource statement.

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 only guidance is parameter-scoped: 'Leave exchange out for every covered exchange,' which tells the agent how to get the full set. There is no statement of when to prefer this tool over siblings (e.g., flows vs ETF flows vs asset metrics) and no exclusions or prerequisites, so usage is only implied by the data description.

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