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

Annotations already flag readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false. The description adds that it appends to outcome_labels scoped to the caller's customer and is plane-only, which is useful. However, it does not disclose idempotency implications (e.g., duplicate appends) or failure behavior, and it contradicts nothing.

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 brief and front-loaded with the core action. The second paragraph adds scoping context without redundancy. It is concise, though the jargon ('label-flywheel substrate') adds slight obscurity.

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?

Given no output schema and low parameter coverage, this description leaves important gaps: it does not specify valid outcome values, behavior when called repeatedly (idempotency consequences), or what the tool returns on success. An agent would need to infer or probe to use it correctly.

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 only 20% (only plane_api_key has a description). The description provides meaning for company_id (the scope of the outcome) and outcome (the conversion label), but leaves observed_at and req_key unexplained. With low schema coverage, the description should compensate more fully; it only partially does.

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 ('Write back') and resource ('a conversion outcome for company_id'), and clarifies the underlying action ('Appends to outcome_labels'). This clearly differentiates it from the sibling tools, which cover watches, company search, and hiring signals.

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?

The description gives context ('Plane session only', 'reads no corpus table') that implies it is for plane-scoped outcome recording, but it does not explicitly state when to use it over alternatives or when not to use it. No alternatives are named.

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