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

No annotations exist, so the description carries the full burden; it does disclose the paste mechanism, formatting preservation, the focus requirement, and a cost signal ('Costs 1 mcp_call'). It omits what happens on failure (no editor focused, non-editable target) and whether existing selection content is replaced or appended.

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 short clauses with the core action first, the target constraint second, and the cost last — no wasted wording. It is terse enough that the omissions feel like under-specification rather than padding.

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?

With no annotations, no output schema, and zero parameter description coverage, the description is the only source of truth and leaves two of three parameters unexplained plus no failure-mode behavior. For a mutation-style UI action that can silently paste into the wrong place, more context is needed.

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 0% across three parameters, so the description must compensate and largely does not: 'html' is only hinted at through the parenthetical, while the 'text' fallback and 'session' parameters are never mentioned. An agent must read the bare schema to learn that a plain-text companion and a session selector exist.

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 concrete verb and resource ('Paste rich text (HTML) into the focused editor') and adds the mechanism ('as a clipboard paste, keeping formatting'), which separates it from a plain fill-type tool. It never names browser_fill, so a sibling differentiation is implied through 'as a clipboard paste, keeping formatting' rather than stated.

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 a real precondition ('Click the target first') and scopes the tool to 'rich-text / contenteditable editors', which tells the agent where it applies. It does not say when to prefer this over browser_fill or browser_press_key, nor what to do when no editor is focused, so the guidance stays implicit.

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