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

The annotations provide almost no behavioral signal beyond non-read-only and non-idempotent. The description adds important behavior: exact-prefix platform detection, fallback to 'Other', and normalization before sending. It doesn't mention duplicate handling or return values, but the disclosed behavior is genuinely useful.

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 sentences with no filler. The core action is front-loaded, followed by the parsing rules and a practical instruction for the agent.

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 single-parameter add operation, the description covers what counts as a known platform, what happens otherwise, and how input is normalized. It omits edge cases like duplicate social links or error responses, but nothing essential is missing for selecting and invoking the tool.

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 the baseline is 3. The description adds meaning beyond the schema's example by explaining exact URL prefixes, the 'Other' fallback, and normalization rules, which helps the agent format account_url correctly.

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 ('Add') and resource ('social link') and immediately gives recognizable URL patterns. It is clearly distinguishable from sibling tools like split_remove_social_link and split_list_social_links.

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 gives useful input-construction guidance, such as normalizing bare handles and passing what the creator gave you. However, it never explicitly says when to prefer this tool over siblings or when not to use it, so usage context is implied rather than stated.

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