send_instagram_dm

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

With no annotations at all, the description carries the full burden. It does usefully disclose supported formats and the 25MB audio cap, but says nothing about Instagram messaging-policy constraints (e.g., the 24-hour customer-service window), permission requirements, whether message_text and an attachment can be combined, or rate limits — meaningful gaps for a send/mutation tool with zero annotation coverage.

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 with the core action front-loaded and no filler; each subsequent sentence adds a distinct capability (threaded reply, audio constraints). Minor room to tighten by grouping attachment-format rules into one clause.

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 6-parameter send tool with no annotations and no output schema, the description covers content types, reply semantics, and audio limits, but omits what the call returns (message ID, status), how errors surface, and whether text plus attachment may coexist — gaps an agent would want before invoking.

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 100%, so the baseline is 3, but the description goes beyond the schema by adding the 25MB size ceiling and naming MP4 alongside AAC/M4A/WAV for audio voice notes. It also frames reply_to_message_id as a threaded-reply control, which reinforces the schema's own wording.

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 opens with a specific verb+resource ("Send a Direct Message ... to an Instagram user by their IGSID") and enumerates the supported content types, so the action is unambiguous. It does not, however, distinguish itself from nearby siblings such as send_instagram_private_reply or send_sender_action, which an agent must infer from the name alone.

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 only implied: the mention of quoting an exact message hints that reply_to_message_id is used for threaded replies, and "by their IGSID" signals the required identifier. There is no explicit when-to-use/when-not statement and no alternative tool is named for cases like replying to a comment versus messaging a user.

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