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

Annotations already cover readOnly/idempotent/destructive, but the description adds genuinely new behavioral context: results are capped at 10, prices are Google list prices from the 2026-10-09 catalog export and are not payable here, USDC is not accepted, and no PDF is returned. That is far more than the annotations provide.

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?

Front-loaded with the core action and return shape, then constraints. Slight redundancy in the three-part negative listing ('does not sell... does not return the PDF... will not accept USDC'), but every sentence carries usable information for an agent.

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?

For a two-parameter read-only search tool with an output schema and full annotation coverage, the description supplies everything needed: scope, result fields, result cap, price caveat, and the handoff action. Nothing required to call it correctly is missing.

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 coverage is 100%, so the schema already documents job (1-500 chars, example) and limit (1-10, default 10). The description adds value by supplying several concrete example job strings and reinforcing the 10-title cap, which helps an agent shape a correct call.

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 (filter) and resource (public ScriptMasterLabs Google Play book catalog) with concrete example queries ('x402 payments', 'options trading'). It also carves out what it is not (a store, a PDF delivery, a USDC payment endpoint), which cleanly separates it from the purchase/x402 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?

Gives clear when-to-use (reader is working on a job) and when-not (buying the book, getting the PDF, paying USDC), plus an explicit handoff instruction: give the human the google_play_url. It stops short of naming a specific sibling tool as the alternative for purchase, so it is not a full 5.

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