Conciseness

Most of the ~490 lines are non-obvious framework specifics that earn their tokens, but the anti-workaround rule is argued twice at length ('Do not have app A generate and execute raw SQL...' in the Rule section and 'Do not switch to a direct action merely because a delegated run is slow or flaky' in Calling), and the Task Lifecycle and Message Parts tables restate standard A2A protocol. This fits anchor 3 ('mostly efficient but includes some unnecessary explanation or could be tightened') more than anchor 4's 'minor instances'.

Actionability

Copy-paste-ready code for the common paths (callAgent, A2AClient, custom mount), an exact manifest JSON with field-by-field rules, exact settings/UI paths, a probe endpoint URL, and failure-mode tables (503/401). Coverage of the common cases is complete and executable, matching anchor 5; the few illustrative fragments (approvedActions) are option-shape examples, not missing steps.

Workflow Clarity

Connection is framed as an explicit two-condition sequence ('two independent things, and both must be true'), and the probe section supplies a verification checkpoint ('reachable-but-unauthorized is the failure worth looking for'). However, much of the document is parallel reference material rather than a sequenced workflow, so anchor 4 ('clear sequence with most checkpoints present; minor validation gaps') fits better than 5.

Progressive Disclosure

Sections are well-labeled and there are no broken or nested references (the only pointers are external URLs and package docs — no references/, scripts/, or assets/ bundle files exist), but roughly 490 lines are inlined in one file, including hosted-provider detail (Foundry, Gemini Enterprise, Anthropic Managed Agents) and a type-export listing that clearly belong in one-level-deep reference files. Anchor 3 ('some structure; content that should be separate is inline') is the best fit; it is not 4 because no splitting has happened at all.

Specificity

The description names three concrete actions — 'discover, authenticate with, and call each other over A2A' — which is specific, but coverage has minor gaps: registration, manifests, and hosted-provider integration are unmentioned. It sits between anchor 3 (1-2 actions) and anchor 5 (comprehensive), matching anchor 4's 'several specific actions; minor gaps'.

Completeness

It explicitly answers both what ('discover, authenticate with, and call each other over A2A') and when ('Use when connecting one app to another, debugging a remote agent that won't authenticate...') with concrete trigger phrases, in third person. This matches anchor 5 exactly; it is not anchor 4 because the 'when' clause is specific and multi-scenario rather than improvable.

Trigger Term Quality

Triggers are natural user phrasings — 'connecting one app to another', 'debugging a remote agent that won't authenticate', 'exposing skills to peers', 'calling agents from scripts' — giving good coverage, though the spelled-out synonym 'agent-to-agent' and terms like 'agent card' are absent. This fits anchor 4 ('good keyword coverage; a few natural terms missing') rather than 5's comprehensive synonym coverage.

Distinctiveness Conflict Risk

The A2A/agent-native scope carves a clear niche with distinct triggers (remote agent auth, cross-app calling), but the body's own 'Related Skills' lists a sibling delegate-to-agent skill whose 'call another agent' phrasing overlaps slightly. Anchor 4 ('mostly distinct; minor overlap risk with closely related skills') fits better than 5's 'minimal conflict risk'.