test_connection

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Marks itself as read-only, which is critical behavioral information. With no annotations provided, the description carries the full burden and adequately communicates the tool's non-destructive nature. No additional behaviors like rate limits need mention for this simple test.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three succinct sentences, each adding value. Front-loads 'Read-only' and states purpose, usage, and arguments efficiently. No wasted words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple test tool with no parameters and no output schema, the description covers purpose, usage, and return value completely. It is self-contained and leaves no ambiguity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Input schema has zero parameters, and description confirms 'No args.' This adds clarity beyond the schema, which is implicit. Baseline for 0 parameters is 4, and the description fulfills this.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Description clearly states the tool verifies a Substack session cookie and returns specific user details (id, handle, primary publication). This verb+resource combination is distinct from sibling tools, which perform different actions like searching or commenting.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly advises calling this tool when other tools return 401 or to confirm setup. While it gives clear guidance on when to use, it does not mention when not to use or provide alternatives, but the context is sufficient for a diagnostic tool.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.