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

Annotations already declare the tool as read-only, open-world, idempotent, and non-destructive, covering safety. The description adds the specific return fields (schema, geometry, record count, capabilities), which is useful but does not disclose potential latency, authentication requirements, or failure modes. This meets the lower bar set by annotations but adds only modest context.

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, front-loaded sentence that starts with the action verb 'Get' and immediately states the resource and output details. Every word contributes meaning, with no filler or redundancy.

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 tool, the description fully explains the tool's purpose and the content of the returned information. It lacks an explicit example of a valid URL format, but the schema's example covers that. Minor gaps include not specifying whether it works with both map and feature services, though the description mentions both. Overall, it is complete for the tool's complexity.

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% with the single 'url' parameter adequately described in the input schema. The description just restates that the tool uses a URL, adding no new semantic information beyond what the schema already provides. This aligns with the baseline 3 for high schema coverage.

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: 'Get an ArcGIS Feature/Map Service layer's schema by url' and specifies the exact outputs: fields (name + type), geometry type, total record count, and capabilities. This distinguishes it from siblings like query_layer, which likely queries data rather than metadata.

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 establishes clear context: use this tool when you need schema information for an ArcGIS service layer, identified by URL. It does not explicitly name alternatives or exclusion scenarios, but the specific verb and resource make the intended use obvious, fitting the 'clear context, no exclusions' level.

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