PromptSharp
Issue #007 · Wed, Jul 1, 2026
Sharpen how you instruct AI — from your first prompt to full agents. |
Prompting for tool use: describe tools like a spec, not a hint
Agents call the wrong tool because the tool was described vaguely. The tool description IS the prompt. |
When a model can call functions/tools, it decides which tool and what arguments based almost entirely on each tool's name and description. Treat every tool description as a mini-spec: what it does, exactly when to use it, when NOT to, and what each parameter means with an example value. The single most common agent bug — calling a tool with garbage arguments — is usually a vague parameter description, not a model failure. |
▸ Copy-paste prompt
Here are your tools. Use them precisely.
TOOL: search_orders
WHAT: Looks up a customer's orders by email.
WHEN TO USE: Only when the user asks about an existing order AND has given an email.
WHEN NOT TO USE: Do not use for general product questions or if no email is provided — ask for the email first.
PARAMS:
email (string, required): the customer's email, e.g. "[email protected]"
status (string, optional): one of ["open","shipped","all"]; default "all"
RULE: If a required param is missing, ask the user for it. Never invent an email.
User: "[paste user message]" |
▸ Level it up
New to this: When an AI tool can 'do things' (search, send, look up), tell it plainly when to use each action and when not to. Clear instructions, fewer wrong moves.
Vibe coder: For each tool, write WHAT / WHEN / WHEN-NOT / params-with-example. The 'when NOT to use' line prevents most over-eager tool calls.
Advanced: Engineer descriptions as the contract: include an example arg value per parameter, enumerate allowed enum values, and add a hard rule 'never fabricate a required arg — ask.' Add a validation layer that rejects malformed tool calls and feeds the error back for self-correction. |
Today's takeaway: Tool descriptions are prompts — write WHAT, WHEN, WHEN-NOT, and an example for every parameter. |
|
▶️ Pro audio
Narrated audio is rolling out
Every issue read end-to-end, plus a private podcast feed for Apple Podcasts, Spotify, or Overcast — landing in your Pro subscription soon.
|
|
Want this done for you — automatically, on every task?
Brainfile installs an AI operating system that runs your business and gets sharper every day.
Meet Brainfile → |
|
Know someone who'd sharpen their prompts with this?
Forward it. Refer 3 friends and we'll send you our private prompt-pack.
Refer & get the prompt-pack → |
|
|
|
|