List metric definitions

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 safety profile is covered. The description adds useful context that results carry Ads Manager display names, but says nothing about result volume, whether the full catalog is always returned, or how filtering narrows output.

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?

Two short sentences, front-loaded with the resource definition and followed by parameter guidance; nothing is padded. The terse phrasing around search matching is slightly ambiguous but no sentence is wasted.

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?

With an output schema present, the description needn't explain return values, and both optional parameters get meaningful coverage. The main remaining gap is workflow context — that this is the discovery step feeding report creation — which an agent would have to infer.

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 description coverage is 0%, so the description must carry the load and largely does: 'search' is described as matching against name or definition with a concrete example ('checkout'), and 'report_type' is given its two legal values, SYNC and ASYNC. It stops short of saying whether search is substring or exact matching, or what happens when report_type is omitted.

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 resource: metric (column) definitions that reports can return, along with their Ads Manager names. It is distinguishable from data-returning siblings like get_analytics or get_keyword_metrics because it yields definitions, not values, though it never explicitly names that contrast.

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?

Usage is only implied: an agent can infer this is a discovery tool to look up metric names, but the description never says to call it before create_report/run_report or that it is the right tool when you need valid column identifiers. No exclusions or alternatives are named.

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