Borrowing it
Nothing to install: this file belongs to s-morgan-jeffries/omnifocus-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/s-morgan-jeffries/omnifocus-mcp/main/.claude/skills/api-design/SKILL.mdgit clone --depth 1 https://github.com/s-morgan-jeffries/omnifocus-mcpWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/s-morgan-jeffries/omnifocus-mcp/api-design)<a href="https://agentmods.dev/skills/s-morgan-jeffries/omnifocus-mcp/api-design"><img src="https://agentmods.dev/badge/skills/s-morgan-jeffries/omnifocus-mcp/api-design/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/s-morgan-jeffries/omnifocus-mcp/api-design"><img src="https://agentmods.dev/badge/skills/s-morgan-jeffries/omnifocus-mcp/api-design.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00061 | $0.01062 |
| Opus 5.5 | $0.00024 | $0.00425 |
| Sonnet 5.5 | $0.00012 | $0.00212 |
| Haiku 4.5 | $0.00006 | $0.00106 |
Grade A, and why
api-design scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 126 lines — stays where its author put it; the contents beside it link to each section on GitHub.
OmniFocus MCP API Design
The API was consolidated from 40+ functions to 16 in October 2025. This consolidation is the project's most important architectural decision. Every new function request must pass through this decision tree.
Decision Tree: Use BEFORE Adding Any Function
Can existing update_X() handle this? (90% of cases: YES)
|-- Setting a field? -> update_task() or update_project()
|-- Example: Flag a task -> update_task(task_id, flagged=True)
|-- Example: Complete a task -> update_task(task_id, completed=True)
|-- Example: Move to project -> update_task(task_id, project_id=X)
|
Can existing get_X() handle this with a parameter? (9% of cases: YES)
|-- Filtering data? -> Add parameter to get_tasks() or get_projects()
|-- Example: Overdue tasks -> get_tasks(overdue=True)
|-- Example: Flagged tasks -> get_tasks(flagged_only=True)
|
Is this truly specialized logic? (1% of cases: MAYBE)
|-- Positioning? Recursive? UI state?
|-- Example: reorder_task() has before/after logic that doesn't fit update_task()
|
If NO to all three: You might need a new function. This is rare.
Anti-Patterns (Never Do These)
Field-Specific Setters
# WRONG - creates API sprawl
set_due_date(task_id, date)
set_flag(task_id, True)
set_estimated_minutes(task_id, 30)
complete_task(task_id)
drop_task(task_id)
move_task(task_id, project_id)
# RIGHT - one comprehensive function
update_task(task_id, due_date=date, flagged=True, estimated_minutes=30)
update_task(task_id, completed=True)
update_task(task_id, status=TaskStatus.DROPPED)
update_task(task_id, project_id=project_id)
Specialized Filter Functions
# WRONG - each filter becomes a function
get_overdue_tasks()
get_stalled_projects()
get_flagged_tasks()
get_tasks_in_project(project_id)
# RIGHT - parameters on the existing function
get_tasks(overdue=True)
get_projects(stalled=True)
get_tasks(flagged_only=True)
get_tasks(project_id=project_id)
String Booleans
# WRONG
update_task(task_id, flagged="true")
# RIGHT
update_task(task_id, flagged=True)
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 126 lines · 61 tokens per session scan A 881b49a6744f
api-design is a skill published in the GitHub repository s-morgan-jeffries/omnifocus-mcp (8 stars, last pushed 5mo ago), licensed MIT. It adds 61 tokens to every session and 1,062 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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