follow_user

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

With no annotations, the description carries the full behavioral burden. It does not disclose that this is a mutating/side-effecting operation, whether it is idempotent when the follow already exists, what error occurs for an unknown user, or what the response contains.

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?

A single efficient, front-loaded sentence with no filler. It is appropriately sized for such a simple tool, though it is arguably too terse to be fully instructive.

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?

This is a low-complexity tool with no nested objects and no output schema, so limited detail is acceptable. However, the zero-required-parameter schema plus the absence of annotations means an agent still lacks the basic facts (at least one identifier needed, idempotency, auth) to call it confidently.

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 both parameters are already documented. The phrase 'by user_id or username' adds a little value by implying the two are alternative identifiers, but it does not clarify that neither is marked required or whether supplying both is legal. Baseline 3 fits when the schema does the heavy lifting.

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?

States a specific verb ('Follow') and resource ('Hardcover user'), plus the two identifier options. It is clearly distinguishable from the sibling unfollow_user by name, though the description itself never names or contrasts the opposite operation.

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?

No guidance on when to use this versus unfollow_user, no preconditions (e.g., authentication, must already exist as a user), and no indication of what happens on repeat calls. The agent must infer everything from the name.

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