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

The description adds behavior beyond the annotations: it discloses that omitting the signal name lists all signals, and it explains the nature of the output ('what it is, why AI agents depend on it, and how to fix it'). This complements the readOnlyHint and idempotentHint annotations without contradicting them.

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 two sentences, front-loaded with the main action and resource, and the optional behavior is clearly stated in the second sentence. There is no fluff, and every word 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?

For a tool with one optional parameter and no output schema, the description is complete. It tells the agent exactly what the tool produces (an explanation of the signal) and how the parameter changes the response (specific signal vs. all signals). Nothing else is needed to invoke it correctly.

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 provides a detailed description of the 'signal' parameter (name, examples, and the omit-to-list behavior). The tool description repeats this information without adding new semantics beyond pointing out the same behavior. With 100% schema coverage, the baseline of 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 uses a specific verb ('Explain') and a clear resource ('one Apirro readiness signal'), and even states the scope of the explanation (what it is, why AI agents depend on it, how to fix it). It also clarifies the alternate behavior of listing all signals when the name is omitted. This clearly distinguishes it from siblings like glossary, pricing, scan, or search.

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 the use case: when you need an explanation of a specific readiness signal or want an overview of all signals, use this tool. It doesn't explicitly mention alternatives or exclusions, but the sibling tools are sufficiently distinct (glossary, pricing, scanning, searching) that the context is clear without stating them.

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