agent_message

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

Annotations only set readOnlyHint=false and openWorldHint=false. The description adds genuinely useful behavior beyond that: message content is untrusted text and never transfers a permission, lease, or task assignment — a security-relevant constraint the agent could not derive from annotations. It stops short of covering TTL/expiry or ack semantics, so not a 5.

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?

Three tight sentences: purpose first, addressing second, safety caveat last. No filler, and the most decision-relevant information is front-loaded.

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 multi-action tool with 11 parameters, a nested object, and no output schema, the description omits how the three actions differ in required inputs (e.g., messageId for ack, to/body for send) and what inbox returns. Purpose and security context are covered, but action-level behavior is not, leaving meaningful gaps.

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 only 27% across 11 parameters, so the description carries real burden. It does clarify the `to` field's addressing syntax ('short name, runtime id or role mailbox such as role:verifier') and implicitly maps verbs to the `action` enum, but leaves kind, ttlMs, taskId, messageId, includeAcked, and the nested agent binding undocumented — partial compensation only.

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?

The description names the exact three verbs (send, read, acknowledge) that map to the `action` enum and a specific resource (a bounded task-scoped message between runtimes). This cleanly separates it from siblings like agent_presence and agent_monitor, which observe runtimes rather than exchange messages.

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?

Usage is implied by 'bounded task-scoped message between runtimes,' giving general context, but there is no explicit when-to-use or when-not guidance and no alternatives named (e.g., when to prefer agent_monitor for observation). Bounded and task-scoped hint at the intended scope, but the agent must infer the rest.

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