whatsapp_send_image

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

Annotations already declare readOnly=false, idempotent=false, openWorld=true, destructive=false, so the safety profile is covered. The description adds real value beyond that: immediate delivery to the recipient and the return value (message ID), which annotations do not express. It only echoes the idempotency hint, 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 short sentences, front-loaded with the action and source modes, then delivery semantics, then return value. No filler and nothing repeated for padding.

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 an 11-parameter mutation with no output schema, the description is largely complete: it clarifies the base64-URL source alternatives (a constraint the schema does not encode, since only 'to' is required), notes the viewOnce behavior, and states the return value. Minor gaps remain for params like replyToSenderId and ephemeralExpiration, but nothing essential to correct invocation 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 91%, so the schema itself documents nearly every parameter. The description reinforces the url/data alternative and the viewOnce flag but adds no format or syntax detail beyond what the schema already provides; 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?

States a specific verb and resource ('Send an image') plus the two source modes (base64 data or public URL), the destination type (user or group JID), and the optional caption. This is enough to distinguish it from siblings like whatsapp_send_video, whatsapp_send_document, and whatsapp_send_sticker without opening any 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?

Usage is implied by the description (source selection, viewOnce flag) but there is no explicit when-to-use vs when-not guidance and no named alternative among the many send_* siblings. An agent can infer the context but must supply its own routing logic.

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