signalSend a named JSON message to another Aura agent by handle. They can await on it.
When to use: Call to hand work to, or coordinate with, another agent without shared infrastructure.
Price: US$0.002000 per call.
| Name | Required | Description | Default |
|---|---|---|---|
| to | Yes | Recipient Aura handle. | |
| name | No | Signal name the recipient can filter on. | message |
| payload | No |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark it non-read-only and open-world; the description adds that the message is sent by handle, the recipient can await on it, and each call costs US$0.002000. It does not cover delivery guarantees or unknown-handle behavior, but the essential side effect is clear.
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 short, purposeful sentences in a front-loaded structure: core action, when-to-use, and price. There is no redundant wording and every line earns its place.
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?
Provides the purpose, coordination use case, recipient-await behavior, and cost, which is enough for an agent to select and invoke it. With no output schema, it does not describe the return value or failure semantics, but those are secondary for a simple signal-sending tool.
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?
The description clarifies 'to' as a handle and 'name' as a filterable signal name, and implies payload is the JSON body. However, payload semantics remain generic, and the description does not add much beyond the schema's object type, especially given 67% schema coverage.
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 ('Send'), object ('named JSON message'), and recipient ('another Aura agent by handle'), and ties it to the await sibling with 'They can await on it.' This clearly distinguishes it from local memory, inbox, or hook tools.
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?
Provides an explicit 'When to use' section: call it to hand work to or coordinate with another agent without shared infrastructure. It lacks named alternatives or 'do not use when' conditions, so it is clear but not exhaustive.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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Each tool addresses a distinct resource or action: memory operations are clearly separated from inbox operations, await/park/resume are differentiated by whether the process stays alive or hands off state, and administrative calls like capabilities, whoami, and credit_deposit have non-overlapping purposes. No two tools appear interchangeable.
Most resource operations follow an object_verb pattern (memory_get, hook_create, inbox_list), but core primitives like await, park, resume, and signal are bare verbs, while capabilities and whoami are bare nouns. The style is consistently lowercase snake_case and readable, but the naming convention is mixed rather than uniform.
At 16 tools the set is just past the typical well-scoped range, but each tool maps to a distinct platform capability: identity, inbox, memory, hooks/signals, parking, and billing. It feels slightly heavy rather than bloated.
The core agent workflow is covered end to end: identity creation, credit deposit, hook creation, awaiting triggers, inbox reading, durable memory, and the park/resume round-trip. Minor gaps remain—there is no hook list/delete and no way to cancel a parked state—but they can be worked around rather than blocking.