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

The annotations already declare this as a non-read-only, non-destructive, idempotent write operation. The description adds useful behavioral context beyond the annotations: both entities must be in the organization and exactly one target must be supplied. The idempotency detail is partly redundant with idempotentHint=true, but the org constraint and exactly-one rule are valuable.

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 compact and front-loaded, using a single sentence to convey the core operation, the exclusive target constraint, the org-scope prerequisite, and idempotency. Every phrase adds relevant information with no filler.

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 three-parameter mutation tool with no output schema, the description covers the essential semantics: target exclusivity, organizational scope, and idempotency. It leaves minor gaps around re-linking behavior and return values, but the core information needed to invoke the tool correctly is present.

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 0%, so the description must carry the burden of explaining all three parameters. It explains project_id and list_id semantics and the exactly-one mutual exclusivity, but site_id is only indirectly implied rather than explicitly described as the site being linked.

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 states a specific verb and resource ('Link a site') and identifies the two possible targets (project_id or list_id), with the exactly-one constraint. It does not explicitly name the sibling unlink_site tool, so sibling differentiation is implied rather than stated.

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 clearly explains the usage context: linking to a project or to a task list, with exactly one target required. It does state the org-membership prerequisite but does not explicitly mention when not to use this tool or point to alternatives such as unlink_site.

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