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

Annotations already state mutation, idempotency, and non-destructiveness, so the description's job is to add update semantics — and it does: "null removes an option" clarifies that explicit nulls strip configuration rather than leave it unchanged, which is the single most error-prone aspect of a partial-update tool. It still does not say that omitted fields are left untouched, nor whether edits are reversible, so a small gap remains.

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 sentences, front-loaded with the resource and the editable surface, followed by the two rules an agent most needs (null semantics, id prerequisite). No filler or restatement of the title.

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 an 11-parameter partial-update tool with an output schema (so return values need no explanation), the description covers the editable surface and the null convention well. The remaining shortfall is the undocumented "reason" parameter and unexplained style/window enum values, which the schema also leaves bare.

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?

With only 55% schema coverage, the description meaningfully compensates: it uses plain-language names for schema keys ("usual range" for baseline, "comparison" for compare_with) and generalizes null-as-removal across the nullable options. It leaves "reason" and "style"/"window" value meanings unaddressed, so it is not fully compensating.

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?

"Change one card" gives a specific verb and a scoped resource, then enumerates the editable facets (title, window, style, comparison, usual range, color, size, change_from, goal) so an agent can map intent to the tool. It does not explicitly contrast itself with the layout/pinning siblings (arrange_home, pin_card), which keeps it 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?

"Call home first for ids" is a genuine prerequisite that tells the agent it must obtain card identifiers before invoking, and "Only when the user asks" is carried in the schema. However, there is no guidance on when to use edit_card versus arrange_home, pin_card, or home, so usage is implied rather than routed.

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