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

With no annotations supplied, the description carries the full burden and delivers: it declares idempotency ('fetching twice is safe') and discloses a real side effect — that echoing wake_id stamps run_started_at on the delivery ledger, proving a run started. It does not mention auth requirements, rate limits, or result ordering, so it is strong but not complete.

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?

Four short sentences, front-loaded with what the tool returns, then safety, then trigger, then pagination mechanics. No filler; each sentence supplies a distinct fact an agent needs.

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?

For a three-param list tool with no annotations, the description covers purpose, trigger, idempotency, cursor semantics, and the wake_id side effect. The remaining gap is return shape — with no output schema, a brief note on what a message row contains would close it.

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 the baseline is 3, but the description adds genuinely new information absent from the schema: that row id is a monotonic sequence, which is what makes after_id a valid cursor. The wake_id meaning is largely duplicated from its own schema description rather than extended.

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 with scope: 'List unacknowledged A2A messages waiting in the grok inbox.' The filtering condition (unacknowledged) separates it implicitly from transmit_ack and transmit_send, but no sibling is named, so differentiation is inferred rather than stated.

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?

'Call this when the inbox webhook fires' gives an explicit trigger condition, and 'Use after_id as a cursor for incremental fetch' tells the agent how to use it in the polling case. It stops short of exclusions (e.g., not for full-history reads or how it differs from transmit_status), so it is clear context without when-not guidance.

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