link_identity

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

With no annotations provided, the description bears the full burden of behavioral disclosure. It adds the merging behavior, which goes beyond a simple link. However, it does not specify side effects like data loss, permissions required, or what happens to the orphan record after merging.

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 description is a single sentence of 14 words, immediately stating the purpose and key behavior. No wasted words.

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?

Given no output schema and moderate parameter documentation, the description covers the core operation and merging behavior adequately for basic understanding. However, it lacks details about the 'orphan record' concept, potential destructive effects, and permissions, which are important for safe invocation.

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 50% (friendId and tenantId have descriptions; provider and externalId lack descriptions). The tool description adds high-level context that parameters are for linking identities, but does not clarify valid values for provider or format for externalId. This is a baseline score given partial coverage.

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 uses a specific verb ('Link') and resource ('external identity to a friend'), and mentions a distinguishing behavior ('merging any orphan record that already holds it (cross-channel unification)'). This clearly differentiates from sibling tools like unlink_identity.

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 description provides no explicit guidance on when to use this tool versus alternatives such as unlink_identity. It implies a use case ('cross-channel unification') but does not state prerequisites or when not to use it.

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