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Dictionary

MCP Tools

MCP tools are typed, described functions an AI model can call — the unit of capability that decides whether an agent is useful or dangerous.

1 min readupdated 2026-08-01

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Each MCP tool has a name, a description, a JSON-schema input and annotations (read-only, destructive, idempotent). The model chooses tools from those descriptions alone, so tool design is prompt design: narrow scope, unambiguous names, small inputs and compact outputs. Write tools should carry approval requirements.

MCP tools are typed, described functions an AI model can call — the unit of capability that decides whether an agent is useful or dangerous. Each MCP tool has a name, a description, a JSON-schema input and annotations (read-only, destructive, idempotent). The model chooses tools from those descriptions alone, so tool design is prompt design: narrow scope, unambiguous names, small inputs and compact outputs. Write tools should carry approval requirements. In practice: `search_orders(customer_email, status)` returning 10 compact rows beats a generic `run_sql(query)` tool that hands the model the whole database. This dictionary node is part of the Onexial knowledge graph and links to related concepts, workflows and tools below.
Definition
Each MCP tool has a name, a description, a JSON-schema input and annotations (read-only, destructive, idempotent). The model chooses tools from those descriptions alone, so tool design is prompt design: narrow scope, unambiguous names, small inputs and compact outputs. Write tools should carry approval requirements.
Example
`search_orders(customer_email, status)` returning 10 compact rows beats a generic `run_sql(query)` tool that hands the model the whole database.
Related Workflows
Related Tool Stacks
Related Prompts
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What is MCP Tools?

Each MCP tool has a name, a description, a JSON-schema input and annotations (read-only, destructive, idempotent). The model chooses tools from those descriptions alone, so tool design is prompt design: narrow scope, unambiguous names, small inputs and compact outputs. Write tools should carry approval requirements.

What is an example of MCP Tools?

`search_orders(customer_email, status)` returning 10 compact rows beats a generic `run_sql(query)` tool that hands the model the whole database.

Why does MCP Tools matter for AI and automation?

MCP tools are typed, described functions an AI model can call — the unit of capability that decides whether an agent is useful or dangerous. It connects to the workflows, prompts and tool stacks linked on this page, so you can move from definition to execution without leaving Onexial.

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Related concepts

The vocabulary this page depends on.

  • MCP (Model Context Protocol)

    Open standard letting AI clients call external tools, data and prompts.

  • MCP Server

    An MCP server exposes tools, resources and prompts from one system so any MCP-compatible AI client can use them over a standard protocol.

  • MCP Client

    An MCP client is the AI-side host that discovers servers, lists their tools and routes the model's calls to them.

  • MCP Resources

    MCP resources are addressable read-only context — files, records, docs — that a client can pull into the model instead of calling a tool.

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Related workflows

Turn this into a repeatable process.

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Related tool stacks

The tools that run it in production.

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Related prompts

Reusable prompts for this job.

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Comparisons & alternatives

Pick between the options.

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