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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds real behavioral context beyond that: result ordering (starred first, then the user's order), per-point position within a sphere, the 200-point page cap, and the presence of 'more'/'next_offset' fields. It does not disclose auth or rate-limit behavior.

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 dense sentences with no filler: contents first, then filtering, then pagination. The most decision-relevant information is front-loaded and every clause carries an actionable fact.

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?

With no output schema, the description must carry return-value semantics, and it does for pagination ('more', 'next_offset') and ordering. It stops short of describing the shape of an individual focus point (identifier, text field), which an agent assembling follow-up calls to update_focus_point would benefit from.

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 baseline is 3, but the description adds meaning the schema lacks: that omitting sphere returns all spheres, that the name match is against a sphere's list, and how offset ties to next_offset in practice. That is genuine added value on top of the schema text.

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 resource (the user's Focus section) and enumerates exactly what is returned: spheres with point counts and focus points with ordering and position. That is far more informative than a tautology, though it never explicitly contrasts itself with the similarly named siblings list_spheres or get_today.

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 conditional usage for one parameter ('Pass sphere to see one sphere only') and a pagination loop ('when more is true, call again with offset set to next_offset'), but says nothing about when to prefer this tool over list_spheres or get_today, which share the sphere/point vocabulary.

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