# Format Selection

> Route to the correct summarization methodology and enforce fidelity rules across all summarization operations.

- Skill: `tools-only/format-selection` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add tools-only/format-selection`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tools-only/format-selection/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Research & Search
- Author: tools-only (https://skillmd.com/u/tools-only)
- Updated: 2026-09-29
- Page: https://skillmd.com/skills/tools-only/format-selection

---

# Summarizer

Route to the correct summarization methodology and enforce fidelity rules across all summarization operations.

## Format Selection

When the user specifies an output format, load the corresponding template before delegating to a domain skill or agent. If no format is specified, default to `structured`.

| User Signal | format_id | Template |
|-------------|-----------|----------|
| (no format specified) | `structured` | [structured.md](./templates/structured.md) |
| "bullet points", "key points", "quick bullets" | `bullets` | [bullets.md](./templates/bullets.md) |
| "tl;dr", "one-liner", "in a nutshell" | `tldr` | [tldr.md](./templates/tldr.md) |
| "json", "machine-readable", "structured data" | `json` | [json.md](./templates/json.md) |
| "table", "tabular", "grid format" | `table` | [table.md](./templates/table.md) |
| "outline", "table of contents", "hierarchical" | `outline` | [outline.md](./templates/outline.md) |

**Loading instruction**: Read `$SKILL_DIR/templates/{format_id}.md` to obtain the schema, example, and fidelity constraints for the selected format. Pass the `format` parameter to the delegated agent or apply the template directly when summarizing inline.

## Decision Tree

When the model needs to summarize content, follow this decision tree to select the correct approach:

```text
INPUT RECEIVED
  │
  ├─ Is it a FILE path?
  │   ├─ Yes → Load file-summarization skill
  │   │         Run file_metrics.py to assess size
  │   │         Select strategy based on size thresholds
  │   └─ No ↓
  │
  ├─ Is it a URL?
  │   ├─ Yes → Load url-summarization skill
  │   │         Fetch content first, then summarize
  │   └─ No ↓
  │
  ├─ Is it an IMAGE (path to .png, .jpg, .gif, .svg, .webp, screenshot)?
  │   ├─ Yes → Load image-summarization skill
  │   │         Read image with Read tool (multimodal)
  │   └─ No ↓
  │
  ├─ Is it MULTIPLE sources (list of files, URLs, or mixed)?
  │   ├─ Yes → Count sources
  │   │   ├─ 3+ sources AND Teammate tool available?
  │   │   │   ├─ Yes → Spawn summarizer team (see Team Coordination below)
  │   │   │   │         Each teammate summarizes one source
  │   │   │   │         Teammates cross-check findings via messaging
  │   │   │   │         Leader synthesizes with multi-source-synthesis skill
  │   │   │   └─ No ↓
  │   │   └─ Summarize each source individually (subagents or sequential)
  │   │             Then load multi-source-synthesis skill
  │   │             Combine with deduplication and attribution
  │   └─ No ↓
  │
  └─ Is it INLINE TEXT (pasted content, agent output, conversation excerpt)?
      └─ Yes → Apply fidelity rules directly
               Use extractive method: identify key passages first
               Produce structured output
```

## Delegation Decision

When the summarization task is autonomous (user asks to summarize something and move on), delegate to a specialized agent:

| Source Type | Agent | When to Use |
|-------------|-------|-------------|
| File(s) | @file-summarizer | Summarizing files without immediate follow-up questions |
| URL(s) | @url-summarizer | Summarizing web content autonomously |
| Image(s) | @image-summarizer | Describing visual content autonomously |

When the summarization is part of the current conversation flow (user wants to discuss the content), apply the relevant skill methodology directly rather than delegating.

**Orchestrator relay**: When receiving results from any summarizer agent, the orchestrator MUST follow the agent-result-relay skill to preserve counts, failure reasons, and structured output. Do not re-summarize agent summaries.

## Team Coordination (Multi-Source)

When the Teammate tool is available and 3+ sources require summarization, the model SHOULD use agent teams instead of sequential subagents. If the Teammate tool is not available, fall back to subagent delegation.

### Workflow

1. **Create team** - `Teammate({ operation: "spawnTeam", team_name: "summarize-{task-id}" })`
2. **Create tasks** - One TaskCreate per source, all independent (no dependencies)
3. **Spawn teammates** - One per source, using the appropriate agent type:

```text
Task({
  team_name: "summarize-{task-id}",
  name: "source-1",
  subagent_type: "file-summarizer",  // or url-summarizer, image-summarizer
  prompt: "Summarize [source path]. Format: {format_id}. When done, send findings to team-lead via Teammate write. If you find information that contradicts another source, message that teammate directly.",
  run_in_background: true
})
```

4. **Collect results** - Leader receives findings via inbox messages
5. **Synthesize** - Leader applies multi-source-synthesis skill to the collected findings
6. **Cleanup** - Request shutdown for all teammates, then cleanup

### When NOT to Use Teams

- Fewer than 3 sources (subagent overhead is lower)
- Sources have sequential dependencies (one source references another)
- User is in a conversational flow and wants to discuss each source

### Fidelity Rules Still Apply

All fidelity rules apply identically to teammate output. The SubagentStop hook validates teammate summaries the same way it validates subagent summaries.

## Fidelity Rules (Mandatory)

These rules apply to ALL summarization regardless of source type. See [Fidelity Rules](./references/fidelity-rules.md) for full details.

**Rule 1: Read Before Summarizing** - Read actual content. Never guess from filenames or paths.

**Rule 2: Extract Before Abstracting** - Pull quotes/passages first, then summarize from extracts.

**Rule 3: Preserve Counts and Specifics** - Keep exact numbers. "7 of 10" not "most."

**Rule 4: Distinguish Absence from Nonexistence** - "Not mentioned in source" not "doesn't exist."

**Rule 5: No Lossy Re-Summarization** - When relaying agent results, relay counts and references. Do not summarize the summary.

**Rule 6: State Confidence Explicitly** - Every summary includes confidence level with rationale.

**Rule 7: Structured Output Always** - Use the format defined in [Structured Summary](./templates/structured.md).

## Output Format

All summaries MUST use structured markdown with YAML frontmatter. See [Structured Summary](./templates/structured.md) for the complete specification.

Required sections in every summary:

1. **YAML frontmatter** - source_type, source_path, method, confidence, word counts
2. **Summary** - the condensed content (BLUF style)
3. **What Was Found** - items discovered with source references
4. **What Was NOT Found** - items searched for but absent
5. **Uncertain** - ambiguous items requiring interpretation
6. **Sources** - full attribution with access dates

## Anti-Patterns

The model MUST NOT:

- Summarize a file based on its name without reading it
- Summarize a URL based on its domain without fetching it
- Describe an image based on its filename without viewing it
- Re-summarize a sub-agent's summary (relay instead)
- Upgrade "not found" to "doesn't exist"
- Drop counts ("7 of 10" → "most")
- Omit the "What Was NOT Found" section
- Present uncertain information as definitive
- Summarize from excerpts (head/tail/grep) without disclosing the limitation