BB Fastmail API
Drives the Fastmail JMAP API for mail, search, bulk triage, sending, masked email, contacts, and calendars. Use when the user mentions Fastmail, JMAP, api.fastmail.com, or a Fastmail API token; when a JMAP call returns 401, 403, `unknownCapability`, `invalidResultReference`, `stateMismatch`, or a `notCreated`/`notUpdated`/`notDestroyed` map; when thousands of messages have to be searched, archived, moved, flagged, or deleted without touching the wrong mailbox; when a draft has to be sent from an alias, identity, or custom domain; when a masked email address has to be created, disabled, or audited; when contacts or calendar events are read or written through JMAP; when an incremental sync or push subscription has to keep a local mirror current; or when a mailbox is being migrated in or out. Not for IMAP clients (`imap`), SMTP delivery (`smtp`), inbox triage as a habit (`inbox`, `email-management`), or Apple Mail on macOS (`apple-mail-macos`).
As a process B 67/100 · Nearly there — weak spots: inputs and preconditions, consistency, running it twice
How to improve
- The SKILL.md body is over 5,000 tokens: move reference detail into references/ and load it when needed.
- Your own cases (evals/evals.json, 4–6 real requests with expected answers): the full check would then run those instead of a model-drafted suite.
- A spec.yaml with trigger phrases and assertions — a behaviour contract for CI; `skilltest init` writes a template.
Guard findings · 0
✓ No critical or high findings
Files scanned: 15. Evidence is masked. Grey chips explain why severity was lowered.
Against the Agent Skills spec
- warning
name-formatname should be kebab-case (lowercase letters, digits, hyphens) - warning
body-longSKILL.md body ≈ 6894 tokens (recommended < 5000); move details to references/ - note
frontmatter-keyunknown frontmatter key "slug" - note
frontmatter-keyunknown frontmatter key "homepage" - note
frontmatter-keyunknown frontmatter key "changelog"
Process rating: all ten parameters 67/100
- 0Inputs and preconditions. Does not say what the process needs to start
- 30Running it twice. 54 mutating operations with no state check
- 40Consistency. Frontmatter name (Fastmail API) differs from the folder (fastmail-api)
- 60Tools and files. Uses tools (web) that frontmatter does not declare
- 60Result and completion. Output format stated, no completion criterion
- 70Execution cost. Instruction body is 6894 tokens
- 100Steps. 41 steps
- 100When it triggers. States when to use and when not to
- 100Failures and branches. 4 branches, has a failure section
- 100Progress reporting. Reports progress
- medium Safety rules and hard prohibitions inside a skill: they belong in the system prompt, here they protect nothing
- low 13 top-level sections: this looks like several domains in one skill
- low The response is described with custom markup (3 tags): a typed call is more reliable
Everything here is measured from the skill text rather than judged by a model, so the numbers are checkable. A parameter weighs more when it is a more common reason for the process to stall.
Quality signals
- +5Description has no quoted example phrases that should trigger the skill
- +3Description length 955: 120–800 characters recommended
- +4No input/output examples
- +1No license
- +2Single-language instructions
- +4Description says when NOT to use the skill
- +4Structure: 13 headings
- +3Step-by-step instructions: 41 items
- +3Output format is stated explicitly
Quality base 70; lint remarks subtract, signals add up to 100. Result: 66.