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

Annotations already cover readOnly, idempotent, and non-destructive, so the bar is lower; the description still adds real value by disclosing the account-key auth requirement and explicitly denying allocation/state-change side effects. It stops short of describing result shape or pagination behavior.

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?

Two terse sentences with the access mode and scope front-loaded and the negative constraint last; no filler or repetition of the title.

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?

A read-only list tool with full annotation coverage and no output schema needs little more than scope, auth, and safety, all of which are present. The only real gap is the undocumented 'search' parameter and any hint about result ordering or pagination defaults.

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 67%: limit and offset are documented in the schema, while the 'search' parameter has no description anywhere. The prose adds nothing about filtering syntax or what search matches against, so it neither helps nor hurts beyond the schema baseline.

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 sending IPs') plus the payload contents ('warmup and state metadata'), which is more than the title alone. It does not distinguish itself from close siblings like sendpost_get_ip or sendpost_list_ip_pools, leaving the list-vs-single-vs-pool boundary to inference.

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?

'READ (account key)' signals the auth context and the closing sentence rules out one misuse (allocating or changing IPs), implying usage. But there is no explicit statement of when to pick this over sendpost_get_ip, sendpost_get_ip_pool, or sendpost_list_ip_pools.

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