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

The description discloses an important side effect: 'on submit it creates the post via create_post.' However, this directly contradicts the annotation readOnlyHint: true. Because the description claims a write behavior while the annotations mark the tool read-only, this dimension scores 1 as an annotation contradiction.

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?

The description is short and front-loaded with the purpose and user flow. The final sentence repeats the idea of interactive UI/composing somewhat, but overall every sentence adds useful routing or behavior context with little waste.

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 one-optional-parameter tool with an output schema and low complexity, the description gives enough invocation context: it explains the interactive UI, channel selection, pre-fill behavior, and delegation to create_post. It could add more about scheduling-edge behavior, but the schema and output schema cover the rest.

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?

There is only one optional parameter, content, and the schema already describes it fully as 'Optional initial text to pre-fill the composer.' The description restates pre-filling in prose, but adds no format, length, or behavior details beyond the schema. With 100% schema coverage, the 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?

The description names a specific action ('Open an interactive composer') and resource ('social media post'), and clarifies the flow up to creating the post via create_post. It also distinguishes itself from the sibling create_post by being the interactive, review-first path.

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?

It gives explicit usage guidance: 'Use this when the user wants to compose a post interactively in a UI' and 'prefer this over create_post when they'd review before posting.' This directly tells an agent when to choose this tool over its closest sibling.

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