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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description goes beyond them by disclosing data provenance and scope — 'the numbers come from one website and describe what these crawlers did here, not across the web' — which usefully bounds what the returned numbers mean.

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 sentences, front-loaded with purpose, then format guidance, then a scope caveat. Every sentence contributes, though the format sentence partly duplicates the schema.

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 carries the return-value burden and does so by naming the payload sections (dated facts, crawler request table, history context, links). Combined with read-only annotations and full schema coverage, an agent has what it needs to call this correctly.

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 parameter already documents both accepted formats. The description restates the same formats with concrete examples (261101, 2026-11-01) and adds the UTC framing, which is marginal value over the schema rather than new semantics.

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 states a specific verb and resource ('Return the daily snapshot of crawler activity on Rattlesnakes By Mail') scoped to one UTC date, and lists the payload contents. It does not explicitly contrast itself against siblings like lookup_crawler or list_changes, but the scope is concrete enough to differentiate.

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: 'for one UTC date' and the accepted date formats tell the agent how to call it, but there is no when-to-use / when-not-use guidance nor any named alternative for looking up crawlers or changes. Adequate but leaves routing to inference.

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