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

Annotations already establish readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: it discloses the deliberate exclusion of SQL internals and, importantly, that a button's index from formdef.buttons[] is what must be passed as action='button:<index>' when submitting.

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?

Front-loaded with the core action and the field inventory, and each clause carries information (contents, buttons/index link, udid source, exclusions). It is somewhat long for one paragraph and the trailing 'EN: show, formdef' tag is filler, but there is little true redundancy.

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 read-only tool with no output schema, the description fully compensates by enumerating the return structure (fields, options, validation, conditions, subforms, buttons) and clarifying what is intentionally omitted. An agent has everything needed to call it correctly and interpret the result.

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 100% schema description coverage and a single parameter, the schema already documents udid as a 32-hex formdef id from list_formdefs. The description only restates that source pointer, adding no syntax or format detail beyond the schema, so the baseline of 3 applies.

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 (read/show) plus resource (formdef) and enumerates exactly what the response contains: fields with key/label/widget/required, options, validation, conditions, subforms and buttons[]. It explicitly names the sibling list_formdefs as the udid source, so an agent can distinguish it from the list/create/save formdef tools.

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?

Gives a clear use case ('pruefst du, ob ein Formular fachlich passt, bevor du eine Action daran bindest') and points to list_formdefs for obtaining the udid. It does not, however, state exclusions against siblings like onto_formdef_save or create, so it stops just short of explicit when-not guidance.

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