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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered; the description adds valuable non-obvious semantics — that a null bid means inheritance from the ad group, and that quality score is absent from the record. It does not mention pagination, result caps, or ordering, which a list tool would ideally disclose.

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 sentences, zero filler, with the field list front-loaded and the sibling redirect placed last as a pointer. Every clause carries information an agent cannot get from the schema.

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 no output schema, the description correctly compensates by naming the returned fields and the null-bid semantics. The only gap is result volume behavior (pagination/truncation) for what may be a long keyword list, which is not addressed anywhere.

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 100% and both parameters (accountId, adGroupId) already document their source tools and when accountId is needed. The description adds nothing about parameters, so the baseline 3 applies — the schema does the heavy lifting.

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?

States a specific verb and resource ('List an ad group's keywords') and enumerates the exact fields returned (id, text, match type, status, bid). It also pre-emptively separates itself from msads_get_keyword_performance, so an agent can distinguish the two without opening either schema.

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?

Explicitly names the sibling tool that should be used instead when quality score is needed, which is a real and non-obvious routing decision in this API (quality score is not on the keyword record). This is the when-not/alternative pattern done correctly.

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