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

Goes beyond the annotations by disclosing insertion position (end of list, or top when 'New first' is set) and a content constraint ('keep it short, in the user's words'). Annotations already cover write/non-destructive/non-idempotent, so this added ordering behavior is real value. It stops short of saying what happens if the named sphere doesn't exist, which matters given openWorldHint=false.

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 terse sentences, lead sentence carries the action and target, subsequent sentences add placement and content constraints. Slightly telegraphic phrasing ('optionally to a Focus sphere and starred') costs a little readability but nothing is wasted.

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?

No output schema, so the description should say what comes back or at least that the tool errors on an unknown sphere; it doesn't. For a simple non-destructive create with three params the core is covered, but the sphere-resolution failure mode and duplicate handling are unaddressed.

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 coverage is 67%, and the description compensates for the undocumented 'text' parameter by specifying length/style expectations ('keep it short, in the user's words'), which the schema's min/maxLength does not convey. It also maps 'starred' to the important flag and notes sphere is optional, adding meaning over the schema's terse hints.

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 and resource ('Add one focus point to the Focus section') and scopes it against the sibling family (add_task, add_goal, add_sphere are all named differently, so the resource is unambiguous). It does not explicitly distinguish this from update_focus_point, but the create-versus-modify split is clear from the verb.

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?

"when the user asks" gives a weak trigger condition but no exclusions or alternatives (e.g., when to use update_focus_point instead, or what to do if the point already exists). Usage is implied rather than specified.

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