[BUG] `AgentConfig.tools` typing is unnecessarily wide

[abrahamcl]

Describe the Bug

AgentConfig.tools accepts an invalid value that should fail type checking. In a static tools map,
each entry should already be a tool object, but TypeScript currently allows a nested resolver
function like myTool: () => realTool.

That compiles without error, even though it is not a valid static tool definition. The bad value
then survives to runtime, where agent.listTools() crashes instead of the mistake being caught by
TypeScript.

Steps To Reproduce

1. Clone the reproduction repo: https://github.com/abrahamcl/mastra-bug-agent-tools

Reproduction

npm install
npx tsc --noEmit

Expected: TypeScript reports an error for myTool: () => realTool.

Actual: tsc exits successfully with no type error.

To show that an actual runtime crash occurs when using the invalid config, run:

npm run test

Link to Minimal Reproducible Example

https://github.com/abrahamcl/mastra-bug-agent-tools

Expected Behavior

Typescript should flag an invalid tool value

Environment Information

System:
    OS: macOS 26.3
    CPU: (8) arm64 Apple M3
    Memory: 128.28 MB / 24.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 25.8.1 - /opt/homebrew/bin/node
    Yarn: 1.22.22 - /opt/homebrew/bin/yarn
    npm: 11.11.0 - /opt/homebrew/bin/npm
    pnpm: 10.32.1 - /opt/homebrew/bin/pnpm
    bun: 1.3.10 - /opt/homebrew/bin/bun
  Browsers:
    Chrome: 146.0.7680.165
    Safari: 26.3
  npmPackages:
    @mastra/core: ^1.24.1 => 1.24.1 
    @types/node: ^25.5.2 => 25.5.2 
    mastra: ^1.5.0 => 1.5.0 
    typescript: ^6.0.2 => 6.0.2 
    vitest: ^4.1.4 => 4.1.4 
    zod: ^4.3.6 => 4.3.6 
  npmGlobalPackages:
    @openai/codex: 0.75.0
    codex: 0.2.3
    httpyac: 6.16.7
    mint: 4.2.60
    npm: 11.11.0

Verification

• I have searched the existing issues to make sure this is not a duplicate
• I have included sufficient information for the team to reproduce and understand the issue

[daneatmastra]

Thank you for reporting this issue! We have labeled it for trio-tb and we will look into it as soon as possible.

If you're experiencing an error, please provide a minimal reproducible example whenever possible to help us resolve it quickly.