slack_stdio_update_message

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the edit scope ('message the user posted') and names the API, but it does not mention permissions, reversibility, error behavior, or what happens when the message_ts is invalid. This is a moderate gap for a mutation tool.

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 with no filler. The core purpose is front-loaded, followed by the API name and required parameters. Every sentence 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?

For a simple three-parameter edit tool, the description covers purpose, the key limitation, and all required inputs. There is no output schema, but a successful edit's return shape is not critical for invoking the tool correctly. Slightly more detail on failure conditions would make it complete.

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 the schema already documents all three parameters. The description adds only a restatement: it names channel_id, message_ts, and 'new message text', and clarifies that message is replacement text. This is baseline-adequate but adds little beyond the schema.

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 and resource: 'Edit a message the user posted', and names the underlying API (chat.update). This clearly distinguishes it from sibling tools like delete_message and remove_reaction, which are different operations.

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 description explicitly notes that 'Hosted Slack MCP can send but not edit', which tells the agent when this custom tool is the right choice. It also lists the required identifiers. It could be stronger by stating when delete_message would be preferred, but the context is sufficiently clear.

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