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

Annotations already declare readOnlyHint=false, destructiveHint=false, openWorldHint=false, so the mutation/safety profile is covered. The description adds genuinely new behavior: directionality (first must be reached before the second opens), a same-period validation constraint, and a failure mode (loops are rejected). It stops short of saying what happens if the link already exists or on invalid IDs.

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?

A single dense sentence front-loads the action and packs direction, precondition, and failure guard into few words. The 'draw an arrow' metaphor costs a little clarity but is compact and earns its place as the core mental model.

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 simple two-parameter link tool with a self-explanatory title and no output schema, the description is adequate on semantics. It leaves gaps on parameter-level constraints, idempotency on repeat links, and error behavior, which matter more here because the schema supplies zero field descriptions.

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 two UUID fields are documented only by name. The description partially compensates by implying direction ('reach the first, then the second opens'), which maps onto from_goal_id/to_goal_id, but it never explicitly ties the ordinal language to the parameter names and omits that both IDs must reference goals of the same period - a constraint that directly affects parameter validity.

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 title gives a plain verb+resource ('Link two goals') and the description specifies the semantics: a directional dependency where reaching the first unlocks the second. It also distinguishes the constraint (same period) and the guard (loops refused). It does not name the sibling unlink_goals, but the purpose is unambiguous.

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?

Usage is implied rather than stated - an agent can infer this is for building goal dependencies, and the 'same period' and 'loops are refused' clauses hint at preconditions. However, there is no explicit when-to-use vs when-not, and no routing to alternatives such as build_goal_flow or unlink_goals.

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