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

Annotations already declare this as a read-only, idempotent, open-world operation, so safety is covered. The description adds genuinely non-structured context: "Keyless" (no auth required) and "Newest first" (result ordering), plus the authoritative-source claim. It does not discuss rate limits or result size beyond what the schema states.

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 tightly packed sentences, no filler, with the purpose, the authoritative claim, and the routing instruction front-loaded in that order. Every clause carries information an agent needs.

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 keyless two-parameter list tool with full schema coverage and no output schema, the description covers purpose, ordering, auth posture, and sibling routing. Nothing required to call it correctly is missing.

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 the descriptions of limit and contains_date already spell out defaults, max, and the date-cover semantic. The description's "with the date range each one covers" describes output content rather than parameter behavior, so it adds little beyond the schema baseline.

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 (list the Common Crawl monthly crawl collections) and even gives a concrete id format example ("CC-MAIN-2026-34") plus what each entry includes. It is clearly distinguished from commoncrawl_index_search by naming that sibling and the dependency between them.

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?

Explicit when-to-use: "call this first to pick the crawl id that commoncrawl_index_search needs," and it flags itself as AUTHORITATIVE for the date-to-snapshot question. An agent knows both the trigger condition and the downstream alternative without inference.

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