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

Annotations already declare readOnly, idempotent, non-destructive and openWorldHint=false; the description reinforces this with 'Local, no network,' which is useful confirmation rather than contradiction. It also discloses the scope of supported error codes, but says nothing about failure modes (e.g., what happens for an unrecognized code).

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 with the purpose front-loaded, followed by input format and scope. No filler, no restatement of the tool name.

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 single-parameter, local, read-only lookup with no output schema, the description supplies purpose, accepted input formats, supported error coverage, and the fact that it returns remediation guidance. Nothing an agent needs in order 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 coverage is 100% and the single param is already described, so the baseline is met. The description earns credit above baseline by clarifying accepted input forms — full error line like "E_NO_STOCK_COUNTRY: ... (req: ...)" or a bare code — which the schema alone does not make explicit.

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+resource ('Explain a Pool Gateway error') plus the follow-on action ('say what to do about it'). This is clearly distinguishable from siblings like pool_get_stock or get_service_status, and an agent can select it without opening the schema.

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?

Gives concrete triggering context: pass the error text your HTTP client got from gw.proxies.sx, or just the code, and enumerates the covered error families (E_AUTH_INVALID, E_BALANCE_EXHAUSTED, E_NO_STOCK_COUNTRY, rate/session limits). It does not name an alternative tool or an explicit when-not-to-use condition, so it stops short of a 5.

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