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

Annotations already cover read-only, idempotent, non-destructive, and closed-world behavior, but the description adds genuinely new context: "no account needed" (an auth requirement that annotations cannot express) and "live" stock. It stops short of exhaustively characterizing the response payload, but it goes well beyond restating annotations.

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; the core capability and the no-account caveat are front-loaded, followed by the mode-dependent output shape and the routing hint. Nothing is redundant with the schema 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?

With no output schema, the description carries the return-shape burden and mostly discharges it by describing counts per mode. Minor gaps remain (no pagination or response-format detail), but for a single-optional-param read tool this is sufficient to call 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 documents the ISO format, so the description's job is to add meaning — which it does by explaining that supplying a country narrows the results to that country's mbl/peer counts and per-class breakdown. That is real semantic value beyond "2-letter ISO country code."

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 ("Get live Pool Gateway stock") and immediately distinguishes itself from pool_build_proxy_url by positioning itself as the prerequisite selection step. The two operating modes (with vs. without a country) are spelled out concretely.

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?

"Use it to pick a pool and country before pool_build_proxy_url" names both the purpose and the downstream alternative, so an agent knows exactly when to reach for this tool versus building the URL. No inference required.

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