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

Annotations already declare readOnlyHint=true, openWorldHint=true, and idempotentHint=true. The description adds behavioral context by specifying possible return states ('supported, contradicted, or insufficient-evidence') and handling of blocked/unreachable sources, which is valuable beyond the annotations.

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 long, front-loaded with the primary purpose, and every phrase adds value. It is concise without omitting critical behavioral states or scope limitations.

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?

Given the simple two-parameter schema, the presence of an output schema, and strong annotations, the description covers the essential behavior including return states and non-general-fact-checker scope. It could have added a bit more detail on expected source snippet formatting, but that is not necessary given the output schema.

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 input schema already provides complete descriptions for both parameters (100% schema coverage). The description reinforces the semantics with 'atomic factual claim' and 'public source URL' but does not add new information beyond the 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 specific verb 'Verify' with a clear resource: 'one atomic factual claim against one public source URL.' It explicitly distinguishes itself from general fact checking with 'Not a general fact checker,' which clarifies its unique scope.

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 clearly states the intended use case (verifying a single claim against a single URL) and provides an explicit exclusion ('Not a general fact checker'). However, it does not name any alternative tools, though none are present in sibling tools.

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