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

While annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, the description adds critical behavioral context not in annotations: '✅ No API key needed — call this now' and the note that 'Every listed tool is callable via tools/call by name — tools/list shows only always-on essentials.' These details inform the agent about authentication requirements and correct invocation, going beyond the structured metadata.

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 compact sentences deliver all essential information: immediate callability, purpose, two usage modes, topic enumeration, and an important invocation-rule clarification. Every clause earns its place, and the most critical detail (no API key) is front-loaded. 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?

For a guide tool, the description covers everything needed for correct invocation: what it returns in each mode, how to supply the optional topic, and how the results should be used (callable via tools/call). With annotations covering safety and an output schema present (not shown here), the description is complete and leaves no gaps for the agent.

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 has 100% coverage of the topic parameter, describing defaults and valid keywords, so the baseline is 3. The description adds value by specifying the output format: 'categorized catalog' with 'name + one-liner' and 'recommended call sequence,' which is not present in the schema. This enriches understanding of how the parameter affects behavior.

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 it is a 'Navigator for the full A2AWire tool surface' that returns a catalog (no topic) or a recommended call sequence (with topic). It uses a specific verb (call) and resource (guide) and distinguishes itself from domain-specific sibling tools by being the meta-tool. The provided topics list and output behavior make its purpose 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?

The description gives explicit when-to-use guidance: 'Call with no topic for the categorized catalog' and 'Pass topic=... for a recommended call sequence.' It also clarifies the invocation distinction between tools/call and tools/list, preventing misuse. The mention of 'call this now' signals immediate applicability, and the topic list acts as a filter for specific flows.

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