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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false. The description adds value by specifying the output components (fields, geometry type, record count, capabilities), which are not in the annotations. It does not contradict the annotations and provides useful behavioral context about what the tool retrieves, though it does not cover rate limits/auth or network behavior.

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 a single sentence that front-loads the verb ('Get') and resource, then lists all key return elements without extraneous words. Every clause earns its place, making it highly efficient and easy to parse.

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 tool with no output schema, the description fully explains what the tool returns (fields, geometry type, record count, capabilities). Annotations cover safety and idempotency. This provides enough context for an agent to select and invoke the tool without missing critical information.

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 has 100% description coverage for the single 'url' parameter, including an example. The description merely says 'by url' without adding new semantic details beyond what the schema already provides. Since the schema does the heavy lifting, the baseline 3 is appropriate; the description does not enhance or clarify the parameter beyond the property description.

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 starts with 'Get an ArcGIS Feature/Map Service layer's schema by url' – a specific verb and resource. It enumerates the exact payload: fields (name + type), geometry type, total record count, and capabilities. This clearly distinguishes it from sibling tools like query_layer (data querying) and search_within (searching), making the 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?

The description clearly implies when to use this tool: when you need schema/metadata of an ArcGIS layer, not actual feature data. It does not explicitly mention alternatives or exclusion cases (e.g., 'use query_layer for data'), but the context is strongly inferred from the explicit return fields and the sibling list. There is no misleading guidance, so it earns a 4.

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