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

Annotations already declare a non-destructive write (readOnlyHint false, destructiveHint false, openWorldHint false). The description adds meaningful context beyond them: the account must already be signed in on the phone at the given slot, and YouTube requires google_email. It still omits failure/idempotency behavior, so it exceeds the annotation baseline without being complete.

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?

Two compact sentences, front-loaded with the primary action, then the key preconditions. No filler sentences; each clause carries actionable information.

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 5-parameter write tool with 100% schema coverage and no output schema, the description covers the platform default, the core prerequisite, and the YouTube-specific requirement. It stops short of describing the result of a successful link, but that is the only notable gap.

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 each parameter (including slot, handle, platform, google_email) is already documented in the schema. The description restates the platform default and google_email requirement but adds no syntax or format detail beyond the schema — the baseline 3 is appropriate.

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?

States a specific verb ("Link a posting account") plus the resource and the platform scope (TikTok, Instagram, YouTube). An agent can distinguish this from update-account-tool, delete-account-tool and list-accounts-tool without opening any 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?

It gives an important precondition (the account must already be signed in on the phone at the given slot), which implies when the tool applies. However, it never names alternatives or states when NOT to use it (e.g. update-account-tool for existing links, or the need to run list-phones-tool first).

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