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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds real context beyond that: the exact-equivalence semantics (no addresses gained or lost) and a per-call price of $0.003 USDC via x402, which is critical operational information for an agent.

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 short sentences with the purpose and output guarantee front-loaded, and the payment note last. Every sentence carries load; nothing is repeated from the title or annotations.

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?

No output schema exists, so the description takes on the return-value burden, which it does ('returning the minimal CIDR list that covers exactly the same addresses'). Combined with pricing and annotation-covered safety, nothing an agent needs in order to call this 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 schema already documents the array-or-comma/space-separated string forms plus the 1000-item cap. The description adds nothing further about the single `cidrs` parameter, so 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 operation (merge/summarize CIDRs) on a specific resource, and pins the exact guarantee: the output covers exactly the same addresses. This cleanly separates it from cidr_split (inverse operation), cidr_contains (membership test), and ip_range_to_cidr (range conversion).

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?

'Route summarization' implies the use case, but the description never says when to prefer this over cidr_split or ip_range_to_cidr, nor any preconditions (e.g. input limits, mixing v4/v6). Implied usage only.

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