Move a tab into an existing tab group

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

With only readOnlyHint=false, the description carries most of the burden and correctly frames this as a mutation that joins an existing group, including the underlying gBrowser.moveTabToExistingGroup call. It does not cover edge behavior such as what happens with an invalid group id, a tab in another window, or whether tab ordering within the group is preserved, so it falls short of full disclosure.

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 sentences, front-loaded with the core action and differentiation before the provenance hint. The inline API name (gBrowser.moveTabToExistingGroup) is marginal value for an agent but does not bloat the text.

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?

No output schema exists, but this is a small two-parameter mutation whose core semantics and id source are covered, and the annotation flags it as non-read-only. Missing only failure-mode and cross-window behavior, which keeps it from a 5.

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%, and the schema already documents both context (default: active tab) and groupId (from browser_list_tab_groups). The description repeats the groupId provenance but adds no syntax, format, or default details beyond the schema; 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 and resource ('Move a tab into a group that already exists') and immediately contrasts it with browser_group_tabs, which creates a new group. An agent can distinguish it from siblings like browser_group_tabs and browser_move_tab without opening the 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?

Explicitly names the alternative ('Unlike browser_group_tabs, which creates a new group, this joins one') and gives the prerequisite step of obtaining the group id from browser_list_tab_groups. The when-to-use condition is unambiguous.

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