Describe a dataset's fields

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the description does not need to cover safety. It adds that the tool returns description, record count, and fields, which is useful behavioral detail beyond annotations. However, it does not disclose potential rate limits, authentication requirements, or error 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 two sentences, front-loaded with the tool's core purpose, followed immediately by the when-to-use guideline. Every sentence earns its place, with no 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?

Given that an output schema exists, the description need not explain return values. It covers purpose and usage context adequately, but could be more complete by mentioning that the tool is read-only or that it works with ArcGIS layers (implied by 'dataset layer') or by noting any constraints. For a simple read-only metadata tool, this is largely complete.

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 'layer_url' parameter, so the baseline is 3. The description implies that the parameter identifies a dataset layer but adds no additional semantics beyond what the schema already provides, such as valid URL formats or constraints. A slight bump to 4 is warranted because the description's mention of 'dataset layer' reinforces the expected input context.

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 clear verb and resource ('Show a dataset layer's description, record count, and fields'), which is specific and distinguishes it from operational siblings like query_dataset and summarize_dataset. However, it does not explicitly differentiate from search_datasets, which also deals with datasets.

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?

It explicitly tells the agent to 'Call this before query_dataset or summarize_dataset to learn field names and types,' providing clear usage context and naming two alternatives. It does not say when not to use it or mention other related tools like search_datasets.

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