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

Goes well beyond the readOnly/idempotent annotations by disclosing consistency semantics ('Both windows come from one SQLite snapshot'), the cutoff definition ('today's latest authoritative finalized cutoff'), and failure behavior ('unavailable coverage returns ErrorV1'). It also flags trust obligations ('Inspect integrity.signed and verify the quantitative attestation before claiming verification'), which an agent could not infer from structured fields.

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?

The comparison scope is front-loaded in the first clause, followed by data-source, return-value, exclusion, and verification sentences in descending order of importance. No sentence is redundant despite the dense jargon.

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 still enumerates the return payload (counts, success rates, exact count difference, percentage change) and the error contract (ErrorV1). It also covers the trust/verification workflow, leaving nothing an agent needs in order to call and interpret it.

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%, but the single parameter is a fixed enum discriminator with no tunable semantics, so the description has little to add. It correctly spends no words on it; only the subtle meaning of the enum constant is undocumented, a minor gap.

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 verb and resource ('Compare native fetchhub-4 transactions TODAY and YESTERDAY') plus the exact comparison basis (same elapsed UTC interval, today's finalized cutoff), which is far more precise than the title. It never names the adjacent sibling (fet112.transaction_activity) that an agent might confuse it with, so differentiation is by scope description rather than explicit contrast.

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?

Provides clear operating context: 'Follow consumer_policy', and explicit exclusions ('No significance test, anomaly decision, cause attribution, forecast or native-chain security assessment') tell the agent when this tool is the wrong choice. It lacks a positive routing statement naming the alternative tool to use for those excluded needs.

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