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

With no annotations, the description carries the full behavioral burden, and it succeeds: it flags that ack is delete, that deletion is immediate and includes message bodies, and that unknown ids are silently skipped. This is strong disclosure of destructive behavior and error handling.

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 front-load the most important safety facts (free, owner-signed, delete semantics) and then cover edge-case behavior. Every clause earns its place; there is 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 destructive mutation tool with no annotations and no output schema, the description covers the essential invocation context: cost, authentication posture, irreversible deletion, and behavior on invalid ids. The schema supplies the nonce/signature mechanics. Nothing critical is missing for correct use.

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 documents address, nonce, and signature well (75% coverage) and message_ids is self-explanatory from its name. The description adds only the 'owner-signed' and 'free' context rather than new parameter-level detail, which is acceptable but not additive beyond schema.

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 specific operation (acknowledge/delete) on a specific resource (read messages) and explicitly clarifies that ack is a destructive delete, immediately removing messages and bodies. This prevents confusion with the non-destructive locker_read/count siblings and resolves the euphemistic 'ack' ambiguity.

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 title and description make it clear this is for acknowledging/removing read messages, and 'Free, owner-signed' signals the operative conditions. It does not explicitly name alternatives or state when not to use it, so it falls just short of a fully explicit routing guideline.

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