send_slack_image

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

No annotations are provided, so the description carries the full behavioral burden. It usefully discloses that uploads render inline and that the path must be a file on this machine, but says nothing about required Slack scopes, file size/type limits, failure behavior, or what the tool returns 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?

Three tight sentences, front-loaded with the action and its distinguishing behavior. Every sentence carries information: what it does, when to use it, and the path constraint.

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 five-parameter upload tool with no annotations and no output schema, the description covers purpose, usage, and the key input constraint well enough to call it correctly. The main residual gap is post-call behavior (success result, error cases), which is not covered anywhere else.

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 all five parameters (title, channel, comment, file_path, thread_ts) are already documented in the schema. The description only reinforces file_path's local-file constraint and adds no new syntax or format detail beyond that baseline.

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 (upload) plus resource (a local image/file into a Slack channel) and it states the distinguishing outcome: content appears inline rather than as a link. That implicitly separates it from send_slack_message, though no sibling is named outright, 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?

"Use for screenshots, diagrams and charts" gives explicit positive usage context, and the inline-vs-link framing hints at when to prefer this over send_slack_message. There are no stated exclusions or prerequisites, so it is clear context without the when-not guidance that would earn a 5.

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