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

Annotations only declare readOnlyHint=false and destructiveHint=false; the description adds substantial behavior beyond that: the new head is a merge commit routed through push gates and thus gets CI, nothing changes on conflict, conflict paths surface in conflictFiles, and auth requirements are spelled out. This is a rich disclosure of mutation semantics and failure behavior.

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?

A single dense paragraph with zero filler and the core action front-loaded before behavior and return details. No bullet structure, and return-field enumeration makes it long, but every clause earns its place.

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 output schema, the description carries the return contract itself — both the success shape ({ok, status, headSha, previousHeadSha, baseSha, url}) and the failure shape with conflictFiles — plus prerequisites and the conflict outcome. An agent has everything needed to call and interpret it.

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 100%, so owner, repo, and number are already fully documented by the schema. The description adds no parameter syntax or format detail, so the baseline 3 applies; it compensates instead by describing the response fields.

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 — bringing a PR branch up to date with its base via a server-side merge of base into head — and explicitly anchors it to the PR page's 'Update branch' action. This distinguishes it from siblings like gluecron_update_pr (PR metadata) and gluecron_merge_pr (landing the PR itself).

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 clear use case and prerequisite conditions: requires write access and 'repo' scope, and explains what it is not (never a force-push). It does not explicitly name alternative tools such as merge_pr or closing/reopening, so it stops short of full when-not/alternative routing.

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