MCP tools and tool discovery
Words made simple
A few useful meanings before you read the explanation.
- MCP
- A shared protocol for connecting AI applications to tools and resources. It does not replace permission checks or application security.
- Schema
- A description of the fields and value types that data should contain. It helps check that an answer has the expected shape.
- Authorization
- Checking what that identity is allowed to read or do. Being logged in does not grant access to every record.
More words from this lesson
- Metadata
- Extra information describing a record, such as its owner, date, policy version or document type.
- HTTP
- The request-and-response protocol used on the web. HTTPS adds encryption to protect information in transit.
Overview
- A tool is a named executable capability with argument metadata and a schema.
- Discovery lets a client obtain the server's available tool descriptions.
- A tool description helps the model choose a capability; it is not proof that the server or tool is trustworthy.
Why this matters
The host can discover integrations without hardcoding a prompt for every operation.
An everyday example
A service desk publishes a menu of tasks with required forms.
A technical example
Discover customer_lookup, order_lookup, ticket_create, and knowledge_search, then expose only authorized ones to the model.
How it works
- Client discovers tools
- Host filters trusted/allowed capabilities
- Model selects name/arguments
- Client invokes
- Server checks schema and policy
- Result returns.
Architecture and flow
Discover → trust/permission filter → model selection → server validation → tool result.
The insurance assistant example
A customer assistant sees read-only claim tools and draft creation; a staff assistant may have additional approved capabilities.
When to use it
Reusable capability catalogs and multi-host tool integration.
When to avoid it
Do not expose every tool from an arbitrary server or trust “read-only” annotations from an untrusted provider.
Interview answer
“Discovery gives tool contracts, not permission. I trust and scope servers, validate calls, and enforce authorization on the server.”
Benefits, trade-offs, and production considerations
- Pin/review tool definitions and detect unexpected changes.
- Schema size affects model context and cost.
- A server can return business errors without a network failure; preserve that distinction.
- MCP tools specification.
Can you explain it without the notes?
MCP tools and tool discovery
Use your own words. Explain an example and one limitation before checking the explanation.
Check your explanation
A tool is a named executable capability with argument metadata and a schema. Discovery lets a client obtain the server's available tool descriptions. A tool description helps the model choose a capability; it is not proof that the server or tool is…
Turn this concept into a clear answer.
Practice this conceptAdapted from 13_AI.MD · “MCP tools and tool discovery”. Examples are study fragments; framework behavior can depend on your version.