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

Annotations already declare readOnlyHint=true, so safety is covered by structured data. The description adds useful behavioral context that the map supports every country and accepts multiple region-identifier styles, but says nothing about what is returned (image vs link), rendering limits, or failure behavior for unresolvable region names.

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 short sentences with the core capability front-loaded and the identifier convention second. No filler, though the parenthetical examples could be trimmed slightly without loss.

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 9-parameter, read-only chart generator with full schema coverage and no output schema, the description covers purpose and the trickiest input convention adequately. The main residual gap is a one-clause statement of what the call returns.

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 description coverage is 100%, so the baseline is 3, but the description genuinely adds meaning beyond the schema: it explains that region values may be names or ISO 3166-2 codes and gives concrete worked examples across two countries. That is exactly the kind of matching rule the schema cannot express.

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?

A specific verb ('Draw') plus resource ('a map of one country with its first-level regions') and the colouring input. The scope limitation to a single country's first-level regions implicitly separates it from world and county-level map siblings, though no sibling is named.

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?

Guidance is about input format rather than when to choose this tool: 'Works for every country' plus region naming conventions. There is no explicit statement of when to prefer generate_county_map, generate_world_map, or generate_pin_map, so the agent must infer the choice from scope wording alone.

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