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

With no annotations provided, the description carries the full behavioral burden, and it does so well for a messaging tool: it discloses that recipients get messages instantly if waiting in slot_inbox, otherwise via their next tool-result header, and that a running browser_wait is interrupted immediately. It omits error/failure behavior and any rate or size limits, but the core delivery semantics are unusually well specified.

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?

The purpose is front-loaded in the first sentence, and the remaining clauses each carry distinct information (targeting, broadcast, delivery timing, usage trigger). It is a dense single paragraph with no filler, though the parenthetical interruptions make it slightly harder to scan than a clean bulleted structure would be.

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?

With no annotations and no output schema, the description must stand alone, and it covers purpose, targeting, delivery timing, and a usage trigger. Missing pieces are minor: what happens on an invalid slot, whether text is persisted or echoed, and confirmation of successful send.

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 75% and the description adds genuine meaning beyond it: 'slot = the slot the recipient owns (to reach another slot's agent, use that slot number)' and 'Omit to to send to everyone on that slot' clarify the slot and to parameters respectively. The agent parameter is left to the schema, which already documents it as the sender's display name.

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 opening sentence states a specific verb and resource: 'Sends a message to other agents (real-time collaboration).' The follow-up clarifies the routing model (slot targeting vs. broadcast). It references slot_inbox only indirectly via delivery behavior, so it does not fully contrast the send/receive sibling pair, but the purpose is unambiguous.

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?

'When you finish a step, notify waiting agents right away' gives a concrete usage trigger, and 'Omit to to send to everyone on that slot' clarifies the broadcast case. However, there is no explicit when-not-to-use guidance or a named alternative for reading messages (slot_inbox is mentioned only in passing as a delivery target).

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