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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety bar is low; the description adds genuine value beyond them by naming the required send_planner.view permission and describing the returned analysis content. Since there is no output schema, this disclosure of return structure is doing real work, though it omits any indication of latency or size of the response.

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?

Purpose is front-loaded in the opening clause, followed by a dense but well-grouped catalogue of what the explanation returns, then short operational sentences. The middle clause is long and list-heavy, but every element maps to actual output content rather than filler.

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 and no annotations covering return values, the description fully carries that burden by naming each section of the explanation, including as_of and reach before/after. Permission requirements, parameter alternatives, and default send_plan behavior are all covered, leaving nothing an agent needs to call 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 100%, so all four parameters are already documented in the schema. The description echoes the sku/product_id alternative and supplies adapter-key examples for network, but adds no syntax, format, or edge-case meaning (e.g. what happens when network matches nothing) beyond what the schema states, so the baseline 3 applies.

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+resource ("Explain why the send plan sends what it does for one product") and enumerates exactly what the explanation contains: velocity × days math, network recommendation deltas, lanes, and 2-day reach. This clearly distinguishes it from get_send_plan (which retrieves a plan) and explain_inventory_gap (which targets gaps).

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?

Gives clear context for use (diagnosing the reasoning behind one SKU's send plan) and stipulates identification by sku or product_id plus an optional network filter. It does not explicitly say when to prefer it over get_send_plan or explain_inventory_gap, so a routing exclusion is missing, but the operating context is unambiguous.

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