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

Beyond the readOnlyHint annotation, the description adds behavioral constraints: 'strict hierarchy traversal', 'coherent parent chain', and 'must not bridge release seams.' It also clarifies that 'No natural-language decoding is performed,' which is valuable context for callers. These details significantly enrich the safety and usage profile.

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?

Four sentences, each earning its place: function, non-goals, use case, and a behavioral caveat. No redundant or promotional language. The description is front-loaded with the core purpose and immediately gives actionable context.

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?

The tool has nested scope objects and 8 parameters, but the schema already documents them well. The description explains the core use case and exclusion behavior. It could optionally mention output structure, but the schema's mention of 'rows', 'counts', and 'limit' covers that. Slightly more could be said about when the scope object is preferred, but overall sufficient.

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%) with informative descriptions for parent_loc_id, admin_level, limit, count_only, etc. The description reinforces the key parameters by naming them ('parent loc_id and target admin level') and adds the no-NL note, which clarifies that admin_level expects structured values. This is a slight value-add over the schema.

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: 'returns descendants from that coherent parent chain' given a parent loc_id and target admin level. It distinguishes itself from the 'mixed-vintage latest-per-depth point resolver' (likely resolve_point), making its purpose unique among siblings.

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 states when to use: 'Use it before shape exports such as every county in a selected parent scope.' Also states what it is not: 'not the mixed-vintage latest-per-depth point resolver' and 'must not bridge release seams.' This gives clear guidance on alternatives and placement in workflows.

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