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

Annotations declare this is a mutating (readOnlyHint=false), non-idempotent, non-destructive, open-world call. The description adds real behavioral detail beyond that: cards render as a small preview top-left, panel values change UI state (cards/board/log/decisions open, none closes), and hard size limits are given. It still doesn't say whether cards accumulate or replace previous ones, which is the main remaining ambiguity.

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?

Purpose is front-loaded in the first clause, kind semantics follow, then UI behavior, then limits — a sensible order with almost no filler. It is dense, packing four distinct topics into a short block, which costs a little readability but wastes no sentences.

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 annotations covering the safety profile and an output schema handling return values, the description carries only what is needed: purpose, kind semantics, panel effects and size limits. The only gap is usage routing versus siblings and whether successive cards stack or replace, which is minor for this tool.

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 two undocumented parameters (`kind`, `panel`) are exactly the ones the description explains in depth: per-kind semantics (code shows a copy button, link must be exactly one http(s) URL, image accepts SVG text or base64 PNG/JPEG/WebP) and per-panel effects. It also restates limits for text, title, SVG and raster sizes. That compensates well for the schema gaps.

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 opens with a concrete verb+resource ("Put a card on the person's call page") and immediately qualifies it with "(never spoken)", which cleanly separates it from the spoken-output sibling `say`. It then enumerates the four card types, so an agent knows exactly what this tool produces without opening the schema.

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?

The "never spoken" qualifier implicitly routes the agent away from `say`, and the panel sentence explains what happens when each panel value is used, including `none` closing them. It gives clear context for use but never names the alternative tool or states an explicit when-not condition.

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