Using MarketCode
Read-only tool
A tool annotated on the server as never changing anything, so an assistant can call it without a confirmation step; every MarketCode tool is read-only.
Also called: readOnlyHint, tool annotations, safe tool.
Definition
Read-only tool, as the data uses it
MCP lets a server annotate each tool with hints: whether it is read-only, destructive, idempotent, or reaches an open world. Assistants use the hints to decide whether to ask the user before calling. Every one of MarketCode's 57 tools carries the read-only hint and a title, and the directory reviews for the ChatGPT and Claude catalogues check exactly that.
Read-only is a statement about side effects, not about cost: a read-only tool can still spend credits, and the description says how many.
Tools
Tools that return it
Property summary
property_summary()One-call summary of a property: what it is, what building it belongs to,
House price index series
market_index_series()The published house-price INDEX for one postcode district or local authority: the level per month (base period = 100), the forecast tail flagged, and provenance saying how the index was built.
See also
Related terms
- Model Context Protocol (MCP): An open protocol that lets an AI assistant discover and call tools on a remote server; MarketCode exposes every data operation as an MCP tool that Claude, ChatGPT, Codex and Cursor can call.
- Credit (MarketCode): The unit MarketCode meters calls in: most tools are free, licensed and model-run tools cost a fixed number per successful call, and one balance covers MCP, REST and the products.
FAQ
Questions about read-only tool
What does Read-only tool mean?
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A tool annotated on the server as never changing anything, so an assistant can call it without a confirmation step; every MarketCode tool is read-only.
Which MarketCode tools return read-only tool?
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Property summary, House price index series. Each runs as an MCP tool in Claude, ChatGPT, Codex and Cursor and as a REST endpoint with an API key, at the same price.
Is tool annotations the same thing?
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Yes. readOnlyHint, tool annotations, safe tool are other names for what this entry defines; MarketCode uses "Read-only tool" in its tool descriptions and responses.
See it on a real address.
Thirty minutes, your property or area, every figure sourced.