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

Annotations already declare the safety profile (readOnly=false, destructive=false, idempotent=false), and the description usefully adds the failure behavior ('conflicts fail') and the re-merge-after-edits trait. It omits permission/rate-limit context, but adds meaningful behavior beyond the structured fields.

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 tight sentences, front-loaded with the core action and constraint, and no redundant restatement of the name or schema. Every clause adds a distinct piece of information.

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 4-param mutation tool with no output schema, it covers the merge mechanism, the precondition, the failure mode, and re-merge semantics. Missing only peripheral details like permission requirements or result shape.

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 only 25% (only projectId documented), so the description carries the burden and does so: it defines the sourceBranch→targetBranch relationship and instructs the caller to set switchToTarget explicitly. It still doesn't clarify what switchToTarget actually does, leaving one param partially opaque.

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 (combine sourceBranch into targetBranch) plus the mechanism (three-way file merge). It clearly distinguishes itself from siblings like diff_branches, create_branch, and switch_branch, which share the branch vocabulary.

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 the precondition that targetBranch must be the version sourceBranch was made from and points to list_branches to find it, plus notes re-merge is possible after edits. It doesn't explicitly route between merge_branch and diff_branches/create_branch, so it stops short of full when/when-not guidance.

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