Conciseness

The body assumes Claude's competence throughout — it never explains what MCAP, Rerun, protobuf, or chunk streams are — and every line carries non-obvious information (decoder interactions, unanchored RE2 regexes, frame_id derivation). Lean with no padding.

Actionability

Copy-paste-ready snippets cover the common cases: `McapReader(mcap_path)` / `reader.stream()`, `.filter(content="/sensors/**")`, `Selector(".joint_positions")`, and diagnostic commands like `reader.stream().to_chunks()` with `Chunk.format()`. The decoder guidance is even backed by a stated verification ("verified: decoders=['protobuf'] alone leaves... a raw :message").

Workflow Clarity

Validation checkpoints are explicit ("Confirm on your file... before deciding anything is missing"; "confirm the defect exists in _your_ data — applied blindly it corrupts") and gotchas include retry loops ("retry with decoders=None to rule out decoder selection"), so the destructive/batch cap does not apply. Not 5 because guidance is organized by topic (API, mapping, gotchas) rather than as a sequenced end-to-end ingest workflow with ordered steps.

Progressive Disclosure

Well-organized sections with effective offloading to sibling skills one level deep (stream mechanics -> rerun-chunk-processing, FK -> rerun-urdf, modeling -> rerun-data-model), and no bundle files exist so nothing is misfiled. Not 5 because the sole concrete reference is a raw external GitHub URL rather than a clearly signaled local reference file, and the dense 6-item gotchas list could live in a split-out reference.

Specificity

"Ingest MCAP files into Rerun chunk streams", "selecting topics or decoders", "decoding custom protobuf messages", and diagnosing "an MCAP-derived stream comes out empty" are multiple specific concrete actions with comprehensive coverage of the skill's domain. Not 4 because coverage is thorough rather than having minor gaps.

Completeness

Explicitly answers what ("Ingest MCAP files into Rerun chunk streams with rerun.chunk.McapReader") and when ("Read when converting an MCAP recording, selecting topics or decoders, decoding custom protobuf messages, or when an MCAP-derived stream comes out empty") with concrete trigger phrases.

Trigger Term Quality

Good natural keyword coverage ("MCAP recording", "topics", "decoders", "custom protobuf messages", "stream comes out empty") that a user working with MCAP data would plausibly say. Not 5 because the ".mcap" file extension and common synonyms are absent; not 3 because far more than 'some relevant keywords' are present.

Distinctiveness Conflict Risk

Clear MCAP-to-Rerun niche with distinct triggers, and it explicitly delimits sibling skills ("Builds on rerun-chunk-processing (stream mechanics) and rerun-data-model"), minimizing wrong-skill triggering.