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

Annotations already declare readOnly=false, destructive=true and non-idempotent, so the safety profile is covered. The description adds real value beyond them: the message is permanently stored, the landlord is notified, it cannot be recalled, and sensitive data types are prohibited.

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?

Three sentences, front-loaded with the action and recipient, then consequences, then the data-handling rule. Minor redundancy: the PII prohibition duplicates verbatim text already in the message parameter's schema description.

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?

With an output schema present, return values need not be described, and annotations cover the destructive/non-idempotent profile. The description supplies the consequential details an agent needs (permanence, notification, no recall) but leaves room_id validity only loosely implied.

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 coverage is 50% and room_id carries no schema description, so the description's 'approved available room' constraint is the only hint about valid room_id values, partially compensating. The PII warning merely repeats the message parameter's own schema description, adding no new meaning.

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 gives a specific verb and resource ('Send and permanently store a message') plus the exact recipient ('the landlord of an approved available room') and the acting identity ('authenticated UniAffitti account'). It is unambiguous versus read-oriented siblings like get_my_conversation_messages or list_my_messages, though it never names an alternative directly.

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?

Usage is implied by the scoping phrase 'approved available room' and the note that messages 'cannot be recalled with this tool,' which hints at deliberation before calling. There is no explicit when-to-use/when-not guidance or named alternative for messaging versus requesting or favoriting.

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