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

Goes well beyond the annotations: discloses that each call is confirmed by default and that confirmation can be toggled off, that messages reach real people and should be user-confirmed, that unsolicited promotional messages are banned, and that a Cotlet API key with app access is required. This is exactly the auth/policy/interaction context annotations cannot carry.

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?

Purpose and the key constraint are front-loaded, and most sentences earn their place. The confirmation guidance is restated twice ('By default you confirm each call' and 'Reaches other people: confirm with the user before each call'), a minor redundancy in an otherwise tight block.

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-param write tool with no output schema, the description covers purpose, scope limits, policy, auth, and confirmation behavior. It stops short of describing what a successful send returns or error handling, but with annotations and schema present, an agent has enough to call it correctly.

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?

Two parameters at 100% schema description coverage, so the schema already documents body and conversation_id (including its source, list_conversations). The description adds no additional parameter-level detail, so the baseline 3 applies.

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?

States a specific verb and resource: reply to a neighbor inside an existing Business Page conversation. It also pins the scope constraint (only in conversations the neighbor started) which distinguishes it from the sibling nextdoor_create_post and list tools. An agent can identify the right tool without opening schemas.

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?

Gives clear context and exclusions: works only in a conversation the neighbor started, and a business cannot message a neighbor first. It does not name the sibling that gets you a conversation_id (nextdoor_list_conversations), but the schema field already points there. Clear when-to-use with a hard exclusion, minus explicit alternative naming.

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