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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, so safety and repeatability are covered. The description adds non-obvious behavioral context the annotations lack: attachments are removed along with the message, which is material for an irreversible operation.

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 two sentences are duplicative ('Delete a message. Delete a message and it's attachments...'), which wastes the first sentence, and the grammar error ('it's' for 'its') slightly muddies meaning. The key detail (attachment deletion) is nevertheless front-loaded and easy to extract.

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 two-parameter mutation tool with no output schema, the annotations plus the attachment-cascade note cover the essentials. It remains incomplete on when the tool should be used, whether deletion is recoverable, and what is returned, so an agent still has gaps before calling it.

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 fully documented in the schema as numeric IDs, so the baseline of 3 applies. The description adds nothing about parameter meaning, format, or how to obtain the IDs.

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 names a specific verb (Delete) and resource (a message) and additionally discloses the cascade effect on attachments, so the agent knows exactly what is being removed. It does not differentiate itself from other delete_* siblings, though the resource name makes the distinction fairly self-evident.

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?

There is no statement of when to use this tool versus alternatives (e.g., list_conversation_messages to locate the target message first), nor any prerequisites such as required permissions. The agent gets no routing help beyond the tool name.

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