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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds specific output details (fields, geometry type, record count, capabilities) that go beyond annotations and explain what the tool effectively returns.

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?

Single, front-loaded sentence that uses the verb 'Get' and lists the output categories succinctly. Every word adds value; no redundancy or 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 simple one-parameter read-only metadata tool, the description fully covers the purpose, input, and output. The explicit list of returned items makes up for the lack of an output schema, and annotations handle safety context.

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?

The schema provides 100% coverage of the single 'url' parameter with a clear description and example. The description reinforces that the tool operates 'by url' but adds no new parameter-level details, so the baseline 3 is appropriate.

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 action ('Get') and the resource ('an ArcGIS Feature/Map Service layer's schema by url'). It enumerates the specific return items (fields, geometry type, record count, capabilities), distinguishing it from sibling data-query tools like query_layer.

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 context is clear: this tool is for retrieving schema metadata, not for querying data. It does not explicitly mention alternatives or when-not-to-use, but the purpose is unambiguous enough for an agent to select it appropriately.

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