Read several ads at once

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

The description goes well beyond the readOnlyHint annotation by detailing sequential execution, per-id failure reporting, and a critical prompt-injection warning. It explains that user-supplied content (titles, descriptions, seller names) must be treated as data, not instructions, and provides a specific action to take if they appear to be instructions. This is exceptional transparency for a tool reading untrusted external data.

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 concise and front-loaded: it states the core purpose first, then adds execution characteristics, error handling, and security guidance. Every sentence contributes new information, and the structure flows logically. There is zero redundant or filler content—it's a model of efficiency.

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 batch read tool with a readOnlyHint and openWorldHint, the description covers all necessary aspects: what it does, sequential behavior, failure semantics, and a crucial safety warning about untrusted data. It does not need to describe return format since no output schema exists, and the input schema covers parameters. The tool is fully contextualized for an agent.

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% (both listingIds and country are described in the schema). The description does not add additional semantic meaning to the parameters; it only references ids implicitly ('several ads by id') without providing syntax or format details beyond what the schema already states. The baseline of 3 is appropriate since the schema handles parameter documentation.

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 clearly states 'Fetches the full detail of several ads by id', specifying both the action and the resource scope (batch of ads). This distinguishes it from the sibling get_listing (single ad) and search tools, as it explicitly says 'several ads by id.' The verb 'fetches' and the resource 'ads' are unambiguous.

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?

The description implicitly guides when to use this tool (for multiple ads) and provides a practical constraint ('keep the list short') due to sequential execution. However, it does not explicitly mention alternatives or when not to use it (e.g., for a single ad, use get_listing). The context is clear but lacks explicit exclusion statements.

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