assert_condition

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

With no annotations provided, the description carries full burden for behavioral disclosure. It does describe the return format ({passed, actual, expected}) and the deterministic nature ('hard pass/fail'). However, it omits details about error handling, timeouts, prerequisites, or side effects, leaving some behavioral ambiguity.

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 (two sentences) and front-loaded with the core purpose. It efficiently conveys key information, though the listing of assertion types is somewhat redundant with the schema enum.

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?

Despite having no output schema, the description mentions the return structure. However, it lacks information on session prerequisites, behavior when the page isn't ready, or error scenarios, leaving some gaps for an agent to fully understand usage context.

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 full descriptions for all parameters (100% coverage). The description adds minimal extra semantics beyond listing the assertion types and mentioning that 'expected' is a string, which is already in 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 clearly states the tool's purpose: asserting a condition on the current page and returning a pass/fail result plus the actual value. It explicitly distinguishes itself from screenshot-based verification with the phrase 'no screenshot to interpret' and lists all supported assertion types.

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 clear context for when to use this tool, calling it 'the verification primitive' and recommending it over screenshot comparison. However, it does not explicitly state when not to use it or describe alternative tools beyond screenshots.

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