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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses two unusual traits: only the first page of results is available, and calls cost $0.002 USDC via x402 while failed calls are free. The cost/charge-on-success detail is genuinely decision-relevant for an agent, though return shape and result ordering are left to the output schema.

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 compact sentences: the first front-loads what is returned and its scope, the second handles exclusions and billing. Every clause carries information; nothing is restated from the schema or title.

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 doesn't need to explain return structure, yet it still summarizes the fields and flags the data gaps and payment model. For a 2-parameter read-only search tool this is close to complete; only the interaction between `limit` and the single-page limitation is unaddressed.

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%, so both `q` and `limit` are already fully documented in the schema. The description adds nothing about parameter behavior (e.g., whether limit interacts with the 'first page only' constraint) and only baseline credit 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?

The description names a specific resource (Chrome Web Store search results) and enumerates exactly what each result contains: name, id, and detail-page link. It also states the source scope (public results page, first page only). It doesn't explicitly contrast with sibling ecommerce tools, but the source specificity makes it distinguishable.

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 implied: search extensions by keyword. The description usefully rules out expecting ratings, user counts or prices, which steers agents away from this tool for enrichment-type queries, but it never states when to prefer a sibling or what prerequisites exist.

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