start_merge

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

Annotations provide no meaningful behavioral hints beyond non-read-only status, so the description carries the burden. It discloses important traits: the call waits for auto-merge to finish, returns a specific merge object, does not reload the editor, and reports conflicts for follow-up. It could go further by noting side effects on the current branch, but the disclosed behavior is strong.

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?

The description is front-loaded with the core purpose, then efficiently packs in blocking behavior, return shape, conflict handling, an editor side-effect note, and an exclusion. Every sentence adds actionable value with no filler.

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?

Even without an output schema, the description specifies the returned merge fields and the conflict-resolution path. It covers when to start a merge, what happens while waiting, how to handle conflicts, and when to use get_merge instead. For a tool with only two documented parameters, this is fully sufficient.

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 the schema already documents sourceBranchId and closeSource. The description adds no new parameter-level detail beyond what is already in the schema, matching the baseline for high coverage. It does reinforce that sourceBranchId is the branch to merge into the current branch.

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?

The description clearly states the tool's specific action: 'Start merging a source branch into the CURRENT branch' and clarifies that the destination is always the editor's current branch. It also distinguishes itself from related merge tools by mentioning the blocking wait and returned merge object, making its role unambiguous.

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?

The description gives explicit workflow guidance: when conflicts exist, use resolve_conflicts then apply_merge. It also explicitly states when NOT to use the tool: 'to inspect an in-progress merge (use get_merge).' This provides clear routing among the sibling merge tools.

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