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

Annotations already cover the read-only/non-destructive/open-world profile, and the description adds genuinely new behavioral facts: the call is paid via x402 and the diff is against a persisted prior snapshot rather than a caller-supplied baseline. It also discloses the return structure (severity + evidence per change). It omits pricing/payment mechanics and first-run behavior.

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 front-loaded elements — pricing model, comparison semantics, then the covered change categories — in a single compact paragraph with no filler. The long enumeration of change types is informative rather than padding.

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 usefully sketches the response (per-change severity and evidence, plus intervening events) and covers the paid-service caveat. It leaves significant gaps for an agent: cost/amount, payment flow, and what is returned or raised when no prior snapshot exists for the address.

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 description coverage is 100% and both parameters carry their own descriptions plus an enum on network, so the schema does the heavy lifting. The description adds nothing about the address or the CAIP-2 network choice (e.g., mainnet vs testnet implications), so the 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?

States a specific verb (compares) and both operands (previous persisted snapshot vs fresh observation) on a Base contract, then enumerates the change categories and evidence returned. It is clear what the tool does, but it never names or contrasts itself with the siblings base_preflight or base_preview, which an agent must distinguish on its own.

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?

Usage is only implied: 'previous persisted snapshot' signals the tool is meaningful only after a snapshot exists, and 'Paid x402 service' signals a cost prerequisite. There is no explicit when-to-use clause, no statement of what happens on a first run with no prior snapshot, and no routing guidance versus the sibling tools.

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