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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so safety behavior is covered. The description adds genuine value with rank/rank_tied/rank_change semantics and the locales breakdown, but return format, pagination and size limits are not addressed. Given the annotation coverage, a 3 is appropriate rather than higher.

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 core purpose and the rank semantics are front-loaded, and every later paragraph earns its place by routing to alternatives or stating auth requirements. The trailing login example is slightly verbose for an agent-facing description but remains actionable.

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 describing return content and does so: listings with latest numbers, tracked keywords with positions, computed rank fields, and locales with keyword counts. An agent can use the result correctly without opening anything else.

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?

Only one parameter, and the schema documents it at 100% coverage ('From list_extensions'). The description adds no further guidance on the required identifier, so baseline 3 applies.

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?

Opens by naming the exact resource and scope: one extension in full, with store listings' latest numbers plus tracked keywords and positions. It distinguishes itself from list_extensions (many) and get_listing (untracked) within the same paragraph.

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 routes to siblings: get_metrics_history or get_keyword_ranks for movement over time, and get_listing for an extension this account does not track. It also states the prerequisite (an ExtensionDash account, with a concrete login example).

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