assert

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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, and the description adds valuable behavioral detail: it polls until timeout, failure raises an error naming the mismatch, and success returns passed and waited_ms. This is useful since no output schema exists, though polling cadence and partial-match failure specifics are not covered.

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?

Three tight sentences, front-loaded with the core verb and polling behavior, followed by pattern syntax and the sibling contrast. No filler; every clause carries information an agent needs.

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 an 8-param, output-schema-less tool, the description covers the essential behaviors: polling, failure semantics, and the shape of success/failure responses, with annotations covering safety. It is close to complete, missing only finer details like default timeout behavior and multi-condition interactions.

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%, so baseline is 3, but the description adds meaning beyond the schema by explaining the pattern syntax (substring vs "/…/" regex) and clarifying that count/containing-text are optional modifiers. These are not stated in the schema field descriptions and improve correct invocation.

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 ('Assert') and resource ('a page condition'), then enumerates the condition types (element exists/visible, text, url/title) so the agent knows exactly what can be tested. It also names and contrasts the sibling wait_for, making differentiation possible without opening either schema.

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?

Explicitly frames the when: recorded flows replay it as a test, and contrasts behavior with wait_for (which returns found:false vs this erroring). This gives a clear selection rule against the closest alternative, though it stops short of stating exclusions for each condition type.

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