describe_resource

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

With no annotations, the description must disclose behavioral traits. It states the tool 'discovers' fields, implying a read-only operation, and mentions it helps build GAQL. However, it does not elaborate on side effects, permissions, rate limits, or response format. The description is minimal but sufficient for a simple introspection tool.

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 concise: two sentences plus an args section. It immediately states the purpose and then explains the parameter. Every sentence adds value, with no fluff. It is well-structured and front-loaded.

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 is simple with one parameter and no output schema. The description covers the purpose and parameter details. It does not describe return values, but for a discovery tool, the context is largely complete. Sibling tools are distinct, so no extra differentiation needed. A slightly richer description of output would improve it.

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 input schema has 0% description coverage, so the description must compensate. It does so effectively by explaining the parameter 'resource' as 'A resource/metric/segment prefix, e.g. 'campaign', 'ad_group', 'metrics', 'segments.' This adds concrete examples and context beyond the schema's type and title, making the parameter's meaning clear.

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 purpose: 'Discover selectable/filterable fields of a resource to help build GAQL.' It uses a specific verb ('Discover') and resource ('fields of a resource'). The tool name 'describe_resource' matches the purpose, and sibling tools (list_accessible_customers, search) are distinct, making the tool's role clear.

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 explains when to use the tool: 'to help build GAQL' and provides example resource prefixes. It does not explicitly exclude other tools or state when not to use it, but given the distinct siblings (search for executing queries, list_accessible_customers for listing customers), the usage context is fairly clear.

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