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

Annotations only mark it non-read-only, non-idempotent and open-world. The description adds substantial behavioral context beyond that: irreversibility ('cannot be taken back'), the 24-hour Instagram window, the side effect of pausing automations for 5 minutes, and explicit recovery guidance on an unconfirmed send.

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?

Five tight sentences, each carrying distinct information (action, irreversibility, time window, side effect, failure handling, auth). Purpose is front-loaded and nothing is redundant.

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?

No output schema exists, and the description compensates by explaining the failure-return case and the correct agent response. Combined with the auth and timing constraints, an agent has everything needed to invoke this 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?

Schema description coverage is 100% and all three parameters are documented there, including the 1000-character limit and the cross-reference to sprkly_list_inbox_threads. The description adds no syntax or format detail beyond the schema, 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 (send/reply) and resource (one Instagram DM to a person who messaged this account, on behalf of the account owner). This clearly distinguishes it from the sibling sprkly_reply_to_comment, which targets a different surface.

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 concrete usage conditions: only within 24 hours of the person's last message, requires inbox access, and the human-in-the-loop step 'show the user the words first.' It also tells the agent what to do on an unconfirmed send. It stops short of explicitly naming alternative tools for other reply channels, so 4 rather than 5.

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