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

Beyond the readOnlyHint annotation, the description adds behavioral context by specifying that only 'active' listings are returned and that the ordering is by 'most recently updated'. This informs the agent of implicit filtering and sorting not visible in the schema. It also implies a lightweight read operation suitable for repeated crawling, which is useful behavioral transparency.

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 two sentences: the first states the core function with a clear verb and resource, the second provides a usage context. There is zero redundant wording, and the most important information is front-loaded. Every word earns its place, making it an efficient and well-structured description.

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 simple list tool with two optional parameters and no output schema, the description is adequately complete. It explains the tool's purpose, the active filter, recency ordering, and typical usage. While it does not specify the return format, the absence of an output schema lowers the burden, and the description covers the essential decision-making information 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?

The schema covers the 'since' parameter with a description, but 'limit' lacks a semantic description. The tool description clarifies 'N' as the limit parameter, effectively adding meaning to it. With 50% schema coverage, the description compensates partly by tying 'N' to the limit, while also hinting that 'since' relates to 'recently updated'. This adds value beyond the raw schema.

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 uses the specific verb 'Return' and identifies the resource as 'N most recently updated active listings', which clearly distinguishes it from siblings like get_listing (specific listing), search_listings (filtered search), and list_agents (agents). The temporal ordering and 'active' filter are explicitly stated, leaving no ambiguity about what the tool does.

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 provides a clear use case: 'Useful for periodic agent crawls', which tells the agent when to choose this tool. It does not explicitly exclude alternatives or list when-not-to-use scenarios, but the context is strong enough to guide selection. The phrase 'periodic agent crawls' implies a polling or regular-check scenario, which is adequate guidance.

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