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

With no annotations, the description carries the full disclosure burden and does deliver ordering ('newest first'), returned fields (cap, channel, running/stopped status) and the read-only nature of the call. It omits pagination/result limits, what happens for an agent with no plans, and any permission scoping, which are meaningful for a list endpoint.

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 compact sentence that front-loads scope and ordering and then enumerates the payload fields; there is no filler and nothing an agent must read past to get the essentials.

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?

With no output schema, the description usefully stands in for the return shape by naming the fields and their status semantics. For a one-parameter read tool this is close to sufficient; only pagination and agent_id semantics are missing.

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 description coverage is 0% for the single agent_id parameter, but the phrase 'this agent' implicitly conveys that the list is scoped to that identifier. It adds no format or constraint detail for agent_id, so it only partially compensates for the undocumented 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?

Names a specific verb (list) and resource (ad plans) and scopes it to 'this agent', so an agent can distinguish it from the singular get_ad_plan or the mutating launch_ad_plan/stop_ad_plan siblings. It does not explicitly name the sibling it is not, keeping it just short of a 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?

Usage is implied by 'Every ad this agent has already launched' and 'Reads only', which signals a safe enumeration call, but there is no explicit when-to-use guidance or routing to get_ad_plan for single-plan detail.

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