AC fetch-price
Search live UK marketplace prices and products from any agent. Use this skill whenever a user wants to find, compare, price-check, or buy a physical product in the UK — e.g. 'find me headphones under £100', 'cheapest portable air conditioner in stock', 'compare prices for a refurbished ThinkPad', 'is this a good deal'. Sends one API call to fetch-price and returns normalised JSON: product name, live price in GBP, condition, marketplace, and a direct purchase URL to give the user. Covers eBay UK now, Amazon UK rolling out. Do NOT use for digital goods, services, non-UK marketplaces, or historical price research.
Search live UK marketplace prices and products from any agent.
As a process C 61/100 · Has gaps — weak spots: result and completion, inputs and preconditions, consistency
What is at stake
Medium-severity findings: the skill is probably honest, but read what alarmed the scanner.
Below is the worst case for this category. The finding here is medium: the guard saw a sign, not a proof.
The instructions or scripts send data out: environment variables, keys, file contents, chat history. You may never notice, because the agent performs the upload as "part of the task".
If the upload is not needed for the task, remove it: catalogs flag such skills and delist them. If it is needed, name the destination explicitly, say what leaves the machine, and give the user a switch.
How to improve
- 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 · 2
✓ No critical or high findings
Medium and low: 2
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medium Exfiltration
net-redirectable-api-keymcp/fetch_price_mcp.py:30Helper sends the API key to a host configured by an environment variable — the key can be redirected to another serverAPI key + configurable base URL from environment
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low Exfiltration
net-credential-usejs/index.js:2Credential used in a network call (verify the destination is the intended service) (the skill's own vendor host)constructor(apiKey = process.env.FETCH_PRICE_API_KEY, baseUrl = "https://api.fetch-price.com") {vendor-host
Files scanned: 8. Evidence is masked. Grey chips explain why severity was lowered.
Against the Agent Skills spec
✓ No remarks against the Agent Skills spec
Process rating: all ten parameters 61/100
- 0Result and completion. Does not say what the result is
- 0Inputs and preconditions. Does not say what the process needs to start
- 0Progress reporting. Says nothing while it works
- 40Consistency. Frontmatter name (fetch-price) differs from the folder (sdk)
- 60Tools and files. Uses tools (web) that frontmatter does not declare
- 100Steps. 5 steps
- 100When it triggers. States when to use and when not to
- 100Failures and branches. 1 branches, has a failure section
- 100Execution cost. Instruction body is 480 tokens
- 100Running it twice. No mutating operations
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
- +3Output format is not stated: the model decides each time
- +1No license
- +2Single-language instructions
- +4Description says when NOT to use the skill
- +3Description length 618: enough signal without eating the budget
- +4Structure: 7 headings
- +3Step-by-step instructions: 5 items
- +4Has examples (2 code blocks)
Quality base 70; lint remarks subtract, signals add up to 100. Result: 88.