regions

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

Annotations already declare readOnlyHint=true and openWorldHint=false; the description reinforces and explains this with 'Makes no network call,' which tells the agent the result is static and safe to repeat. It also adds domain context on what the regions actually represent (modern voivodeships plus Warsaw, Ukraine, Belarus, Lithuania, 'other'), which goes beyond the 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?

Front-loaded with the action and the no-network caveat, then the downstream usage, then domain detail. Three short sentences with no filler. The historical mapping sentence is narrow but earns its place by disambiguating a common lookup.

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 must indicate the return content, and 'region codes and names' does so adequately. For a zero-parameter static lookup, nothing essential is missing; only an indication of result size or format would improve it marginally.

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?

Zero parameters, so the baseline is 4. The description still adds value by clarifying that the returned codes are the value domain for the `region` parameter of sibling tools, and by giving a concrete mapping hint ('Most of the Prussian Provinz Posen is 15wp') that prevents incorrect code selection.

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 ('List Geneteka's region codes and names') and immediately names the downstream consumers (geneteka_coverage, geneteka_search). An agent can tell this is a reference-lookup tool rather than a search tool without inspecting 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?

Explicitly tells the agent what to do with the output: 'Pass a code as `region` to geneteka_coverage or geneteka_search.' That establishes the call sequence. It stops short of an explicit exclusion statement (e.g. 'do not guess codes, call this first'), so it is strong context rather than a full when/when-not rule set.

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