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

Beyond the annotations (readOnlyHint=false, openWorldHint=true), the description discloses that this reaches other people (an external customer), that user confirmation is required before each call, the failure precondition, and the specific API-key requirement with app access. These are exactly the behavioral facts an agent needs and none are inferable from the structured fields.

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 core action and the 'lead must be marked hired' constraint are front-loaded, but the constraint is stated twice and the confirmation/API-key notes read as filler. It is functional but not tight.

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 an outbound mutation with no output schema, the description covers the precondition, the external-recipient confirmation requirement, and auth needs. It omits only what a successful call returns, which is minor given no output schema exists.

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, but the description adds a meaningful validity constraint on lead_id: the lead must already be marked hired or the call fails. That enriches the parameter beyond the schema's sourcing hint.

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 names a specific action and resource: invite a customer who hired you to review you on Bark. That is clear enough to separate it from siblings like bark_send_message or bark_send_estimate. It stops short of explicitly contrasting with those alternatives, so it lands at 4 rather than 5.

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 states a concrete precondition — the lead must be marked hired, otherwise the call fails — which tells the agent when the tool is valid. It does not name alternatives or when-not-to-use cases, so it is clear context without exclusions.

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