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

Adds substantial behavior beyond annotations: text fully replaces the old content, mentions are recalculated from mention tokens, attachments are wholesale replaced ([] clears all), an 'edited' mark appears, and only one edit is permitted. These replacement semantics and the edit-window limit are exactly the facts an agent needs before committing.

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?

A single dense sentence that front-loads the edit constraint and then enumerates replacement behavior with no filler. Every clause carries operational meaning.

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?

With annotations covering the safety profile, a 100%-covered schema, and no output schema expected to be explained, the description supplies the remaining gaps: ownership, time window, replacement semantics, and irreversibility. Nothing needed to invoke it 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 baseline is 3, but the description adds the '[] removes all' convention for attachments and clarifies that mentions are derived from tokens rather than passed explicitly. The full-replacement semantics for text and attachments also give context the schema only implies.

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 (Edits) and resource (the token owner's own regular message) with an explicit scope restriction that separates it from chat_send and chat_message_delete. An agent can identify the operation and its boundary without opening the 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?

Gives concrete use conditions: only the owner's own message, only within 60 minutes of sending, and later edits being impossible tells the agent this is a one-shot operation. It does not name alternative sibling tools for the 'too late' or 'not my message' cases, so it stops short of 5.

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