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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the bar for added behavioral disclosure is lower. The description adds real value: it explains the data semantics around stale sources, clarifies what does and does not count as signal, and notes that the tool is free and does not charge credits. No contradiction with annotations.

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 dense but every sentence earns its place: core listing behavior, returned fields, the critical stale-source caveat, sibling routing, and cost behavior. It is front-loaded with the main action and keeps the most important caveat early.

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 carries the burden of explaining return values, and it does: eventCount, unclassifiedCount, staleSources, and Source health fields. It also explains the account scope and how the returned keyword IDs feed other tools, making the tool fully callable and interpretable.

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 tool has zero parameters and the schema is empty, so the baseline is 4. The description correctly focuses on the resource shape instead, defining the returned metrics and the nested Source health fields, which is more useful than parameter documentation would be here.

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 names a specific verb and resource ('List every keyword on the account') and immediately distinguishes itself from get_keyword, which provides full configuration. The scope is unambiguous and clearly differentiated from siblings.

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 positions itself as the starting point: 'Start here: a keyword id is what get_keyword_results, get_keyword_events, list_keyword_buckets and keyword_manage take.' It also routes to get_keyword for full configuration and warns to report stale sources before drawing conclusions from mentions. It does not exhaustively contrast with all listing siblings, but the key routing is present.

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