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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds valuable context beyond annotations by explicitly stating it does not download malware samples, a critical behavioral trait users must know. It also hints at recent temporal scoping.

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 sentences, no filler. The first sentence states the core function and output type; the second clarifies a key boundary. Every word earns its place and front-loads the essential information.

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 one optional parameter fully documented in the schema, the description is complete. Annotations cover the read-only, non-destructive nature. The description adds the crucial 'no download' caveat, leaving nothing an agent needs to call it correctly.

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% for the single 'limit' parameter, so the schema already fully documents it. The description adds no additional parameter semantics, which is acceptable given the high coverage.

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 ('list'), resource ('payloads'), and scope ('recently observed by URLhaus'), plus the type of data returned ('metadata and cryptographic hashes'). This clearly distinguishes it from sibling tools like urlhaus_recent_urls (which lists URLs) and urlhaus_lookup_payload (which likely looks up a specific payload).

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?

Provides clear context: this is for recent payloads and returns metadata/hashes. Explicitly states what it does not do ('does not download malware samples'), which is an important exclusion. It does not name specific alternatives, but the scope is unmistakable.

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