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

Beyond annotations, it discloses the cross-scope validation failure mode (400) and the security rationale, the required right (can_manage_scope on scope_id, admin exempt), the absence of a roles parameter, and the return payload (saved id plus re-read row). With destructiveHint=true already flagged, the description adds the missing context about what is mutated and who may do it.

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, then preconditions, then permissions and return values in a single dense paragraph with no filler. The trailing English keyword line ('start card, save, team card') is search-oriented rather than informative, a minor cost.

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?

There is no output schema, and the description compensates by naming both returned fields (saved id and karte). For a 4-parameter upsert with a permission gate and a scope constraint, nothing an agent needs to call it correctly 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 coverage is 100%, so baseline is 3; the description nevertheless adds meaning by tying id to create-vs-update, stating the 400 consequence of a cross-scope iface, and defining title's empty-value fallback. Much of this restates the schema text, which caps it at 4 rather than 5.

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 first clause states the verb and resource and the exact create-vs-update discriminator: 'Startkarte anlegen (id weglassen) oder aendern (id setzen)'. An agent can distinguish this upsert from onto_startcard_delete, onto_startcard_move, and onto_startcard_index without opening any 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?

It gives concrete when-to-use semantics (omit id to create, set id to modify) and a hard precondition (iface must come from onto_startcard_index.interfaces in the same scope). It does not explicitly point at move/delete as alternatives for other operations, but the create/update routing is clear.

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