AgentObserver — Agent Health & Preflight

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.

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

With no annotations provided, the description carries the full behavioral burden. It does disclose notable traits: the operation is paid, returns fresh evidence, and is machine-readable. However, it leaves the core 'Paid Preflight' pairing ambiguous — whether the call itself charges money or is a no-cost dry run before a payment — and says nothing about failure modes such as an unregistered counterparty.

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 front-loaded sentence where the decisive qualifier 'Paid' appears first and every word is functional. The only minor waste is 'Preflight' repeating the tool name, keeping it just shy of a top score.

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 simple two-parameter tool with no nested objects, the description is minimally adequate, but there is no output schema and no annotations to lean on. It leaves important operational context unstated: what the machine-readable evidence looks like, whether a call actually debits funds, and what happens if the target is not registered.

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 100% and both parameters are well documented (target is a registered counterparty URL, max_age_seconds explains freshness and offers a usage hint). The main description adds only the conceptual tie between 'fresh' and the max_age_seconds parameter, so the baseline of 3 applies.

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 states a concrete action ('return') and resource ('fresh machine-readable evidence about a registered AI-agent counterparty'), which is distinct from sibling tools that deal with interfaces, status, and targets. However, the 'Paid x402 Preflight' prefix partially restates the tool name and leans on unexplained jargon ('x402', 'evidence'), so it falls short of full clarity.

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 context is implied rather than explicit: the word 'Paid' signals cost is a consideration, and 'fresh evidence' implies the trigger is needing current counterparty data. It does not name alternatives, state when not to use the tool, or suggest a sibling for other scenarios.

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

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

No annotations are provided, so the description carries the burden of explaining behavior. It discloses that the tool is free and that it shows status information rather than modifying anything, but it does not explicitly confirm absence of side effects or whether checking reachability triggers network requests.

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?

A single sentence that front-loads the key facts ('Free preflight status') and packs the output contents and intended use into compact clauses with no filler.

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 one-parameter tool with an output schema, the description covers what the tool reports and when to call it. The only notable gap is not distinguishing it from the sibling preflight 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 schema already describes the single parameter fully (100% coverage), so the description adds little beyond restating the use case in the schema. Baseline 3 is appropriate.

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 identifies a specific action ('show') and resource (status of a registered counterparty), and enumerates concrete output dimensions: freshness, reachability, material changes, and review reasons. It is clear, though it uses 'preflight' which overlaps with the sibling tool agentobserver_preflight, so it doesn't fully distinguish itself.

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?

It gives a clear use context: 'before relying on or paying a registered counterparty.' However, it does not explicitly name alternatives or say when not to use it, leaving some routing to inference.

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

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

With no annotations, the description carries the full burden of behavioral disclosure. It clearly conveys a read-only listing operation with a dynamic 'currently' filter, but it does not mention authentication needs, pagination, or other side-effect details. This is adequate but not thorough.

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 clear sentence with no filler. The core action and filter are front-loaded, making it immediately scannable for an AI agent.

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 parameterless list tool with an output schema available, this description is complete. It states exactly what is listed and under what condition, and the output schema handles return-value details.

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, so the schema fully covers all inputs and the baseline is 4. The description adds no additional parameter meaning, but none is needed.

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 uses a specific verb ('List') and a specific resource ('registered AgentObserver counterparties'), plus a clear qualifier ('currently have paid Preflight enabled'). This makes it easy to distinguish from sibling tools like agentobserver_status or agentobserver_interfaces.

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 implies when to use the tool: whenever a caller needs the set of counterparties with paid Preflight enabled. However, it gives no explicit guidance about when not to use it or which sibling tool to prefer in other scenarios.

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