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

Annotations already declare destructive/non-idempotent/non-readonly, but the description adds cost consequences (per-SMS-part billing, account credit spent), irreversibility ('Not undoable'), a legal/compliance constraint against unsolicited messaging, and the underlying API call shape. This is substantial context beyond the structured hints.

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?

Front-loaded with the 'WRITE' flag and the money cost, which is what an agent most needs. The remaining content is dense and occasionally overloaded with punctuation, but nearly every clause carries a distinct constraint 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?

Covers cost, limits, compliance, and irreversibility for a mutation tool with no output schema. The one gap is that it never says what comes back (e.g., a message ID usable with messente_get_delivery_status), which would help chaining, but otherwise nothing essential is 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 coverage is already 100%, so the baseline is 3, but the description adds real semantic constraints on `to` ('one message per recipient, never to a list') and clarifies that the cap is per call, not per message broadcast. Sender default behavior is left 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 ('SENDS REAL SMS TEXT MESSAGES') with explicit scope ('SMS only', one message per recipient). An agent can distinguish this immediately from siblings like messente_get_prices, messente_check_blacklist, or messente_get_delivery_status.

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 explicit when-to-use conditions (send to opted-in recipients only, max 10 recipients, no lists) and routes the agent to the pricing sibling for pre-send cost estimation. Compliance boundaries are stated as prohibitions, not hints.

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