Move a tab into the current split view

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

Annotations only supply readOnlyHint=false; the description adds real behavioral context beyond that: the same-window constraint ('in this window') and the hard prerequisite that a split view must already exist, which is the main failure mode. It stops short of saying what happens on failure or that a split view holds limited tabs, so it is not exhaustive.

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-loaded with the action and its prerequisite; three short sentences with no filler. The final sentence partially restates the create-first guidance, a minor redundancy, though it usefully frames the sibling relationship. The parenthetical API name is low-value for an agent.

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 one-optional-parameter mutation tool with no output schema, the description covers purpose, precondition, window scope and the sibling alternative — enough to call it correctly. Missing only edge behavior such as what error occurs with no split view or capacity limits.

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% — the single context parameter is already documented as 'Tab to move (default: the active tab)'. The description adds nothing about the parameter, so the baseline 3 applies.

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+resource (move a tab into the already-open split view) with a window scope, and explicitly distinguishes itself from browser_split_view, which creates a new split view from two tabs. An agent can select between the two 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 an explicit precondition ('Requires an existing split view — create one first with browser_split_view') and names the complementary alternative with the condition that separates them. This is when-to-use and when-to-use-something-else in two sentences.

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