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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds that this opens a client-facing UI for the user rather than returning data to the model, which is genuinely useful context, but it says nothing about focus behavior, state changes, or side effects on the user's session.

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 tight sentences: the capability is front-loaded and the usage constraint follows immediately. No filler or repetition of the schema.

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 zero-required-parameter, read-only UI opener with full schema coverage and no output schema, the description covers what the tool does and when to use it. The only real gap is sibling disambiguation against open_project_board.

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 the single optional project_slug parameter is fully documented in the schema, including the omit-for-default behavior. The description mentions browsing "their projects" but adds no syntax, format, or default detail beyond the schema, so the baseline 3 applies.

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 ("Open") and resource ("the Stele app") plus the surfaces it exposes (projects, tasks, activity, search), so the agent knows this launches a browsing experience. It does not, however, differentiate itself from the sibling open_project_board, leaving some ambiguity about which opener to pick.

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 a clear positive condition ("when the user wants to see or browse their project") and an explicit exclusion ("not to answer a question"). It stops short of naming the alternative tool to use for question-answering, but the routing intent is clear.

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