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

Annotations already cover the mutation profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false), so the bar is lower. The description still adds real value beyond them: the (network_id, name) uniqueness constraint tells the agent a conflict is possible on duplicate names, and the required write scope discloses an auth prerequisite the annotations do not.

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, each carrying distinct information — purpose/scope, geometry format, constraints/auth. The core purpose is front-loaded with no filler.

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 six-parameter create tool with full schema coverage, no output schema, and annotations declaring the mutation profile, this covers purpose, geometry format, uniqueness, and permission requirements. The only omission is any indication of what a successful response returns, which is minor given no output schema is declared.

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%, so the baseline is 3, but the description adds meaning the schema does not: it explains the semantic relationship between network_id and name as a composite key, and clarifies the Polygon-vs-MultiPolygon decision rule (separate pieces, e.g. a rail corridor or an island) rather than just restating the type.

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 (Create) plus resource (operational hydraulic boundary) and defines the domain concept with concrete examples — pressure zone, DMA, sewershed. An agent can distinguish this from siblings like create_service_area or create_infrastructure_network 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?

The description supplies a prerequisite ('Requires infrastructure_zones:write scope') and a uniqueness rule, which implicitly tells the agent when creation will succeed, but it never states when to choose this tool over alternatives (e.g. create_service_area) or when not to use it. Usage is implied rather than directed.

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