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

Annotations already cover read-only/idempotent/safe, so the description sensibly spends its budget on domain behavior: it explains what each status means and that no-answer/busy typically triggers a WhatsApp fallback, and that blocked means no credit was consumed. That is real value beyond the structured fields, though it says nothing about ordering or pagination.

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 purpose sentence, then usage, then a status glossary, then args — a logical progression where each block earns its place. The status list is dense but justified for interpretation of results.

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?

An output schema exists so return values need not be described, and annotations carry the safety profile; the description fills the remaining gaps (when to use, status meaning, parameter range). For a single-parameter read tool this is complete.

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 0%, so the description must carry the parameter. It supplies the meaningful constraint missing from the schema — the 1-50 range — plus the record-count meaning, while the default is already present in the schema. Slightly more (what 'recent' means, ordering) would be ideal.

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 ('Show recent delivery history') and immediately scopes it to calls, sent messages, and misses. This is distinguishable from list_reminders/get_reminder, which are about reminder configuration rather than delivery outcomes.

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 triggering questions ('did it call me?', 'why didn't I get it?') and the diagnostic purpose of confirming a reminder is firing. It stops short of naming when NOT to use it or pointing to an alternative sibling, so it misses the top band.

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