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

Given the readOnlyHint annotation, the description adds substantial behavioral context beyond it: strict hierarchy traversal, coherent parent chain, the restriction on bridging release seams, and the absence of natural-language decoding. These traits describe how the tool behaves, not just that it is read-only.

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 description is four sentences, each earning its place. It opens with the core behavior, adds a contrast, gives a concrete use case, and closes with a limitation. No filler or repetition.

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 moderate-complexity tool with 8 parameters and no output schema, the description covers the essential conceptual model and usage. It does not explain optional parameters like bbox/limit/count_only, but the schema descriptions handle those. The core semantics and constraints are well-covered, though a bit more detail on return shape would push it to 5.

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 high (88%), so the baseline is 3. The description adds meaning by highlighting the key inputs 'parent_loc_id' and 'target admin level,' and clarifying that no natural-language decoding is performed, which gives extra semantic nuance to the admin_level parameter beyond the schema's examples.

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 clearly states the tool's function with a specific verb and resource: 'Strict hierarchy traversal... returns descendants from that coherent parent chain.' It distinguishes itself from the sibling resolver by explicitly contrasting with the 'mixed-vintage latest-per-depth point resolver,' making its unique purpose unambiguous.

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?

Usage guidance is explicit: 'Use it before shape exports such as every county in a selected parent scope.' It also provides exclusions: 'must not bridge release seams' and 'No natural-language decoding is performed,' clarifying when not to use it and differentiating from natural-language tools.

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