Get Card Builder card by ID

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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds genuinely non-obvious behavior: there is no dedicated get-by-id WebSocket command, so it fetches the whole collection via card_builder/cards/list and matches client-side. It also documents the exact not_found error payload, which neither annotations nor the schema convey.

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?

Well front-loaded and sectioned (behavior, Use when, Returns, Errors), so an agent can scan it quickly. Slightly verbose in re-explaining the client-side fallback matching, but every line still carries signal.

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 single-parameter read tool with an output schema, the description covers what is returned ('same shape as one entry from card_builder_list_cards') and the error case. Nothing needed to invoke or interpret the call is missing.

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 card_id parameter is fully documented there, so the baseline is 3. The description only lightly reinforces this by noting that matching accepts the legacy card_id field, which is useful but marginal over the schema.

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 ('Get one Card Builder card by id, including its full config'), which cleanly separates it from siblings like card_builder_list_cards or card_builder_update_card. An agent can identify the operation 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?

Provides an explicit 'Use when' clause tying the tool to a downstream action (inspecting/copying config before update_card or renderer_card_config). It lacks an explicit when-not or a direct contrast against card_builder_list_cards, which is the nearest alternative.

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