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

Annotations already cover read-only/idempotent/non-destructive, yet the description adds substantial behavior: rules resolve like useNextOpenSlot, linked URLs report the base URL's rule with linkedToUrl naming it, null means spacing does not constrain the URL, and rules can only be changed in the dashboard. It also preempts a likely misconception by stating an explicit sendAt is not an exemption from later respacing.

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?

Trigger conditions are front-loaded and the routing alternative and account-selection caveat come at logical points. It is dense and runs long, with the sendAt and dashboard sentences sitting slightly off the core lookup purpose, but each still conveys usable behavior rather than 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?

With an output schema present, the description needn't enumerate return fields, yet it still explains the null case and the linkedToUrl field's meaning. For a two-parameter read tool, an agent has everything needed to call it correctly and interpret the result.

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 both parameters are documented structurally; the description adds meaning by tying url to the same value create_post accepts and explaining linked-URL base resolution. That is genuine added semantics, though it does not elaborate further on accountId beyond what the schema states.

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 and resource: returns the Pin Spacing rule (DEFAULT or CUSTOM) that Tailwind applies to Pins linking to a given URL, including spacing in days. It explicitly contrasts with list_pin_spacing_rules (all rules at once), so an agent can separate the two without opening schemas.

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?

Opens with concrete trigger conditions ("how far apart Pins will be spaced," "why Pins land days apart," "whether Pin Spacing will get in the way of a planned cadence") and names the alternative tool for the adjacent need. It also gives an explicit procedural rule: if multiple accounts exist and the user did not pick one, ask rather than choose.

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