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

Annotations declare readOnlyHint=false and destructiveHint=false but say nothing about the edit window. The description's "WhatsApp only accepts an edit within about 20 minutes" is genuine behavioral context an agent cannot get from the annotations. It stops short of describing failure modes or what happens to the original message on success.

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?

Two short sentences, purpose first and the critical constraint second, with zero filler. Every clause earns its place.

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?

An output schema exists, so return values need not be explained, and all four parameters are documented in the schema. What remains thin is the post-window behavior and confirmation of whether the edit replaces or appends — small gaps for a low-complexity single-object tool.

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 each parameter already carries its own description including provenance (wa_list_accounts, wa_send_message), so the schema does the heavy lifting. The description adds no parameter-level meaning beyond "the replacement message body" implied by "edit". Baseline 3.

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 ("Edit a WhatsApp message") and scopes it to messages "you sent", which cleanly separates it from wa_send_message, wa_delete_message, and wa_get_message without naming them. It does not explicitly point at a sibling alternative, so it falls short of a 5.

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?

The 20-minute window is an implied usage condition, but there is no explicit when-to-use guidance and no mention of what to do instead when the window has passed (e.g. delete and resend). Usage is inferable but not stated.

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