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

Without annotations, the description must carry the full burden. It discloses the two-step flow and the security note 'Never ask for a password,' which is valuable. It does not cover edge cases like failure modes, rate limits, or what happens after linking, leaving some behavioral gaps.

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?

Three tightly written sentences with zero waste: purpose first, then the interaction flow, then a critical security note. The description is front-loaded and every sentence earns its place.

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 the tool's simplicity (one optional parameter, no output schema, no annotations), the description adequately explains the linking process and the need to call again after approval. It could mention what happens after linking or error handling, but for an agent to invoke correctly, it is nearly complete.

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?

The single parameter `link_code` is fully described in the schema (100% coverage), so the baseline is 3. The description adds the context to call again with the link code, but does not provide additional syntax or format details beyond the schema.

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 ('Links') and resource ('this agent to the person's account'), making the purpose clear. It does not explicitly name the sibling tool `unlink_account` as the alternative, but the opposite action is evident, so an agent can distinguish it without opening the 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?

The description implies the usage: call to get a link, have the person sign in and approve, then call again with the link code. However, it does not explicitly state when to use this tool versus alternatives or provide exclusions, leaving the agent to infer the context.

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