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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), so the bar is lower. The description adds genuine value beyond annotations: 'HTML is inert untrusted content and is never rendered by Ausca' warns the agent that HTML in the message must be treated as data, not trusted markup — a useful security-relevant disclosure. The word 'normalized' hints at a transformation, though its exact meaning is left unexplained.

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?

Two short sentences with no wasted words. The core function is front-loaded in the first sentence, and the second sentence earns its place by adding security-relevant behavioral context about HTML handling.

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 is simple (two required params, read-only, output schema present), and the annotations fully cover the safety profile. The description covers the core operation and a key security caveat. Minor gaps remain — what 'normalized' means and error/not-found behavior — but for a simple read tool with rich structured metadata, it is largely complete.

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 0%, so the description must compensate for the two undocumented parameters. It does not: inbox_id and message_id are never explained beyond their self-evident names and the prefix patterns (^inb_, ^msg_) in the schema. 'One bounded normalized message' weakly connects to message_id selecting a single record, but the description carries essentially none of the parameter-semantics burden.

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 and resource: 'Return one bounded normalized message.' This makes the singular-read purpose clear and implicitly contrasts with the plural sibling ausca_agent_inbox_messages. However, it doesn't explicitly name or differentiate from siblings, leaving the agent to infer the distinction from tool names alone.

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?

No explicit when-to-use or when-not-to-use guidance is provided. The description does not route the agent to siblings such as ausca_agent_inbox_messages for listing, ausca_agent_inbox_attachment for attachments, or ausca_agent_inbox_delete for removal. The only usage signal is the weak implication that 'one bounded' message means single-message reads, which is not substantive guidance.

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