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

With no annotations provided, the description carries the full burden of behavioral disclosure. The verb 'Discover' implies a read-only operation, but the description does not explicitly state that there are no side effects, nor does it mention any authentication requirements, rate limits, or response behavior. For a tool with zero parameters, the risk is lower, but the lack of explicit behavioral context is still a deficiency.

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 description is a single, efficient sentence that front-loads the primary purpose ('Discover all public AgentObserver interfaces') and then provides the enumerative details. There is no filler or redundancy.

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?

The tool has an output schema (context signals indicate has output schema: true), so the description does not need to explain return values. The zero-parameter schema and simple discovery purpose make the description sufficient for a basic understanding, though it could optionally mention whether it requires any prior setup or authentication, but given the output schema coverage, this is acceptable.

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 tool has zero parameters and the schema description coverage is 100% (trivially, since there are no properties). Per the guidelines, a baseline of 4 is appropriate when there are no parameters, as there is nothing for the description to elaborate on.

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 clearly states the verb 'Discover' and the resource 'all public AgentObserver interfaces', and enumerates the specific interface types (HTTP/x402, MCP/x402, A2A). This is specific and distinguishes it from siblings like preflight, status, and targets, which cover other aspects of the system.

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?

The description provides no guidance on when to use this tool versus the sibling tools (preflight, status, targets). It does not mention any context or conditions that would make this the appropriate choice, nor does it exclude alternatives. This is a gap for an agent deciding between multiple tools.

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