board_custom_fields

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

No annotations are provided, so the description carries the full burden. It adds one genuine behavioral note — that dropdown/list options are included only 'when Trello returns them', signalling conditional/incomplete payloads — but says nothing about read-only semantics, auth requirements, rate limits, or the shape of returned definitions.

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?

One sentence, front-loaded with the 'Use when' trigger and no redundant restatement of the tool name. It is efficient, though the qualifier 'when Trello returns them' is slightly ambiguous about whether options are opt-in.

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 simple one-parameter read tool with no output schema, the description does convey the gist of the return (definitions plus conditional options). It still leaves the agent guessing about what a definition contains and whether assigned field values are included, which matters given no output schema to fall back on.

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% for the single boardId parameter, so the schema already documents its meaning. The description's phrase 'known Trello board' reinforces that boardId must reference an existing board but adds no format, ID source, or validation detail beyond 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?

The description gives a specific verb ('inspecting') and resource ('custom field definitions on a known Trello board'), so the agent knows this lists board-level custom field definitions rather than field values. It does not name or differentiate against close siblings such as custom_field_get, board_field_get, or custom_field_options, which is exactly where confusion is likely.

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 'Use when inspecting custom field definitions on a known Trello board' clause establishes a clear trigger condition. However, it offers no when-not guidance and does not route the agent away from custom_field_options, even though it explicitly mentions returning dropdown/list options — an overlap that invites misselection.

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