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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuine context beyond that: the call requires no authenticated store context and works without a selected channel, and it returns visible sources with publication permissions, HasAutoOrder and AutoOrderingFee. It does not explain pagination or result-size behavior, keeping it below the top mark.

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?

The purpose and usage constraints are front-loaded, but the text carries internal metadata (ownerAgent, supportingAgents, Domain, Entity, Operation, Scope, AllowedIntents) and a duplicated trailing "Search terms: sources getpublic" that do little for an invoking agent. It is informative but noticeably padded rather than tightly written.

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 read tool with full annotation coverage and an output schema, the description covers purpose, selection conditions, exclusions, country-code format and observable results. It is complete enough to invoke correctly; the only remaining gap is pagination or result-set size behavior, which is minor given the output schema exists.

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 schema itself only says "HGRApi query parameter isoCountry", so the description meaningfully compensates: it specifies that the value is a two-letter HGR country code inferred from the marketplace or country named by the user, with IT for Italy as a concrete example. The parameter is effectively enum-less, so this disambiguation of format and derivation adds real value.

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 verb and resource: lists visible supplier/source marketplaces and their capabilities for a requested country. It also distinguishes itself from generic callers ("This is an explicit tool with a fixed endpoint; it is not a generic endpoint caller"), though it never explicitly contrasts with the nearby siblings like hgr_get_sources, hgr_get_sources_get or hgr_get_catalog_getproductsource, so the differentiation is only partial.

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?

It provides an explicit "Use when" block covering commercial and pre-sales questions about suppliers, publication methods and Auto Ordering fees, plus a "NegativeUseCases" block that excludes claiming a supplier account is configured for the current user or listing private suppliers. The conditions that select this tool over alternatives are spelled out rather than left to inference.

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