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

Annotations already declare this as destructive and non-idempotent. The description adds useful behavioral detail beyond that: the first row retains its name while the other rows are removed, and only straight rows on one line are eligible.

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?

The description is front-loaded with the core operation, followed by concise usage boundaries and a relevant example. Every sentence earns its place.

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 destructive three-parameter mutation with no output schema, the description covers the operation, eligibility, and removal behavior. It does not describe the response or error cases, but those gaps are minor.

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?

Schema coverage is 100%, so the baseline is 3. The description adds meaning by implying that rowIds order matters ('the first keeps its name') and provides an example showing the expected rowIds and expectedUpdatedAt shape.

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?

The description states a specific verb and resource: join straight rows on one line into one row. It also distinguishes the operation from its inverse, split_row, by explaining that the first row keeps its name and the rest are removed.

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?

It gives explicit when-to-use guidance ('a row was built in pieces') and when-not guidance ('rows across an aisle'). It does not name the exact alternative tool for the excluded case, but the boundary is clear.

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