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

Annotations mark this as a non-read-only, non-destructive mutation but say nothing about side effects. The description supplies the key behavioral fact that 'Creating never sends anything' — the create is safe because it only makes a draft — plus a platform-availability constraint. It does not add auth/permission, rate-limit, or idempotency context beyond the annotations, so it falls short of a 5.

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 tight sentences with zero filler. The most important constraint ('DRAFT ... never sends') is front-loaded, followed by the workflow and then the platform exclusion.

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-param draft-creation tool with no output schema, the description covers purpose, sequencing with the two companion tools, the ID source, and platform limits. Nothing an agent needs in order to call this 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?

Schema description coverage is 100%, so every parameter (name, tags, text, accountId, description, isSubscribed) is already documented in the schema, including the note that accountId comes from list_broadcasts. The description's 'Use an accountId from list_broadcasts' merely repeats what the schema already says, so baseline 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?

Specific verb+resource ('Create a broadcast DRAFT') with an immediate gloss on what a broadcast is ('a DM sent to many contacts at once'). It clearly separates this from its siblings send_broadcast and add_broadcast_recipients, so an agent can select it without opening either schema.

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?

Explicitly states the full workflow: create the draft, add people with add_broadcast_recipients, then deliver with send_broadcast. It also gives the prerequisite ('Use an accountId from list_broadcasts') and the exclusion ('Not available on WhatsApp or LinkedIn'). When-to-use, when-not, and alternatives are all covered.

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