set_attribute

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

No annotations, so the description carries the full burden, and it delivers unusual depth: cross-agent rejection with TAB_NOT_OWNED, a configurable action cap with default and range, and a declared change_report payload naming the exact mutated fields (URL, dialogs_opened, nodes_added/removed, attrs_changed, inputs_changed, focus_shift) plus truncation behavior and fallback. It stops short of stating permission/auth requirements or whether the attribute is created when absent.

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?

Front-loads purpose, then when-to-use, related tools, multi-agent caveats, and returns in a logical order. The RETURNS paragraph is long but justified because there is no output schema; a sentence or two of it could still be tightened.

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 7-param mutation tool with no annotations and no output schema, the description supplies the return shape, the error path (TAB_NOT_OWNED), the cap, and tab ownership rules. Remaining gaps are minor: no statement of failure behavior for a non-matching selector or whether a missing attribute is created.

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%, so all seven parameters are already documented, including tab_id auto-resolution and the client allowlist. The description's tab_id sentence largely restates the schema, adding no syntax or format detail beyond it; baseline 3 is appropriate.

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?

Opens with a specific verb+resource ("Set an HTML attribute value on an element") and immediately names the complementary siblings get_attribute and get_dom_snapshot, so an agent can place it against the many DOM/input siblings without reading schemas.

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?

Explicit when-to-use list (form manipulation, hidden field values, ARIA state toggling, data attributes) plus named alternatives with their conditions: get_attribute to read first, get_dom_snapshot to find selectors. Also gives the tab_id selection rule explicitly (pass only when owning multiple tabs).

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