step

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

There are no annotations, so the description bears the full burden. It discloses that the tool returns 'the resulting page state with a new screenshot' and that there is a 'Smart selector fallback' that tries alternative strategies on CSS selector failure. However, it does not discuss potential side effects of actions, whether they are reversible, or any error handling beyond the fallback, which is a notable gap for a tool that executes mutations.

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 about 100 words, starts with a clear lead sentence, and lists actions in a compact block. The v0.3 version note adds useful behavioral information but is somewhat tangential to core usage. Overall, it is efficient without being bloated, scoring a 4.

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?

The tool is moderately complex with 8 parameters, no output schema, and no annotations. The description covers the core purpose, action categories, and a key behavioral fallback, and the schema fills in parameter details. However, it does not explain the session lifecycle (e.g., that a session must exist before this step), nor does it describe the response format beyond 'resulting page state with a new screenshot'. Given the sibling tools (start_session, end_session), a brief usage context would improve completeness.

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 provides descriptions for all 8 parameters (100% coverage), including the action enum and values for `value`. The description adds no new parameter-level semantics; it only restates the action list and mentions optional recording of persona thoughts/friction, which are already described in the schema. Therefore, it aligns with the baseline for high schema 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?

The description clearly states 'Execute one step in a session' and enumerates nine specific actions, distinguishing it from sibling tools by focusing on action execution and returning a screenshot. It uses a specific verb (execute), a resource (one step in a session), and a scope (list of actions), which makes its purpose unambiguous.

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 implies usage within a session ('Execute one step in a session') and lists actions, but it does not explicitly state when to use this tool versus alternatives like get_page_state or auto_walk, nor does it provide exclusions or alternative recommendations. The context is clear but not prescriptive.

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