click_mark

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

With no annotations, the description carries the full burden and does so well: it explains that web content is clicked through the page's own JS engine, that an Accessibility press is a silent no-op on web content, native controls go through the AX tree, and otherwise it falls back to a center-coordinate click. It also warns that mark numbers go stale when the UI changes.

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 dense sentences that are front-loaded with the core purpose and the preferred alternative. Every clause conveys operational information, though the mid-sentence branch description is slightly heavy to parse.

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 2-parameter tool with no annotations and no output schema, the description covers activation mechanics, fallback behavior, staleness risk, and the recommended alternative. Nothing needed to invoke it correctly is missing.

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 the baseline is 3, but the description adds lifecycle semantics the schema lacks: mark numbers are ephemeral and go stale on UI change, requiring a fresh read. The background-only fallback nuance is left to the schema, which documents it adequately.

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 (activation/click) plus the exact resource it consumes (the mark NUMBER from the most recent ax_read/read_ui or screenshot(marks=true)). It explicitly differentiates itself from the preferred sibling ax_activate, so an agent can route correctly 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?

Gives explicit when-to-use ('Prefer ax_activate with snapshot_id/node_id because it rejects stale generations') and a concrete precondition ('run a fresh ax_read immediately before acting'). The alternative and the reason to choose it are both named.

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