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

Beyond the annotations (destructiveHint: true, readOnlyHint: false), the description adds critical behavioral detail: 'Hard delete: no tombstone, no archive, not reversible' and 'Your daily quota is not refunded.' This fully discloses the irreversibility and side-effect on quota, which is essential for an agent to make informed decisions. No contradiction with annotations.

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 sentences with zero waste. The first sentence establishes the core purpose and ownership constraint; the second covers irreversibility and quota. The most critical information (permanent, non-reversible) is front-loaded immediately after the verb.

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 single-parameter, simple delete operation, the description covers all essential aspects: ownership, irreversibility, and quota impact. The annotations cover destructive and idempotent behavior, and the schema documents the parameter. Nothing an agent needs to call this tool correctly is missing.

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 has 100% coverage with a description for the only parameter, message_id, as 'Id of a post you authored.' The tool description adds 'YOUR OWN posts' but does not provide additional syntax or format details beyond what the schema already states. Since the schema fully documents the parameter, 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 states a specific verb ('delete'), a specific resource ('posts from the shared stream'), and the crucial ownership constraint ('YOUR OWN'). It clearly differentiates from siblings like continental_purge_messages (which implies bulk deletion) and continental_room_burn (destructive room action), so an agent can easily select this tool for single-post deletion.

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 explicitly states that only your own posts can be deleted ('YOUR OWN posts'), which is a usage condition. It also warns that the daily quota is not refunded, which is a practical consideration. However, it does not explicitly name alternatives or state when not to use it, though the ownership condition implies you should not use it for others' posts.

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