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

Annotations already establish readOnly and non-destructive, so the description focuses on what structured fields can't convey: the agency-key auth requirement and the surprising server-side default that start_date becomes today. That default is a genuine behavioral trap an agent would otherwise miss. It doesn't discuss rate limits or response envelope, keeping it at 4.

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 short sentences, each earning its place: scope, auth gate, parameter gotcha, then the endpoint. The most consequential constraint (agency key only) is front-loaded.

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 read-only list tool with a fully described 6-param schema, the description covers auth, scope, and the one non-obvious default. With no output schema, the return shape and pagination envelope (next_page) are unstated, but the schema's page description partially compensates.

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 earns an extra point by disclosing the default-to-today behavior of start_date and its filtering semantics (creation date), which the schema omits. The page/per_page pagination params are left entirely to the schema.

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 and resource ('list the profiles') and even defines what a profile is ('websites/campaign sets') scoped to one account. An agent can distinguish this from whatconverts_get_profile or whatconverts_list_accounts without opening the schema.

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?

'Agency key only' is an explicit precondition that determines whether the agent can call this at all, which is high-value guidance. It stops short of naming an alternative (e.g. 'use get_profile for a single profile'), so it is not full when/when-not routing.

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