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

Beyond the annotations it discloses the key behavioral trait: repeated calls do not create a duplicate edge but update it, which is upsert semantics an agent could not infer from readOnlyHint=false alone. It does not describe the response or any permission requirements, but the write/upsert profile is the important addition.

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?

The three German sentences are front-loaded and mostly earn their place, but the trailing '| EN: object, record, entry, property, link, search' keyword block is search-optimization padding with no value for tool selection.

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 mutation tool with no output schema, the description covers the write behavior, idempotency-like semantics, and both related tools. Remaining gaps, such as return value or requirement of linkvalue for certain link types, are minor.

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 all six parameters are documented in the schema. The description adds nothing about linktype syntax, when linkvalue vs linkvalue_free applies, or what scope_id does, so it neither compensates nor detracts.

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?

Specific verb and resource: connects two objects via a link type, creating an edge. It is clearly distinguishable from onto_object_update_link, which the description names as the tool for changing existing edges.

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 routes the agent to onto_link_index for available link types and to onto_object_update_link for modifying existing edges, which is explicit alternative guidance. It does not, however, clarify the overlap between this tool's own upsert behavior and update_link, leaving an ambiguity about which to pick for an existing edge.

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