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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint. The description adds meaningful context by noting the data scope ('global table', 'active routes'), the best-route-versus-all-routes behavior, and the query cost ('Costs 1 query'). No contradiction exists.

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 tight sentences deliver purpose, scope, output details, alternative tools, and cost with no filler. The core purpose is front-loaded before the routing guidance.

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?

The description is complete for this tool's complexity: it explains what the tool does, when to choose it, what distinguishes it from siblings, and its cost. An output schema exists, so return-value detail is not required here.

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%, so the schema fully documents both 'prefix' and 'all'. The description references the 'all' behavior ('when asked, every route-server view') but does not substantially add semantics beyond the schema's parameter descriptions. This matches the baseline for full schema coverage.

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 action and resource: retrieving active routes in the global table for a CIDR prefix, including origin AS and AS path. It also explicitly distinguishes itself from pwhois_lookup_ip and pwhois_asn_prefixes, making sibling differentiation immediate.

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?

The description gives explicit when-to-use guidance: use this tool when you have a CIDR block. It names the alternatives for single addresses and for an AS's full prefix set, so an agent can route correctly without extra reasoning.

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