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

Beyond the annotations (readOnlyHint=false, idempotentHint=true), the description discloses operational behaviors that materially affect invocation: the link expires in 10 minutes, works only once, requires a fresh call for a new link, and corrects handle typos to the authorized username. These details add real context and are consistent with the annotations, so there is no contradiction.

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?

Four dense sentences, each earning its place: purpose, browser workflow, expiry/single-use semantics, and the professional-account prerequisite. The most important information — what the tool does and why — is front-loaded in the first sentence with zero 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 no output schema, the description still conveys what the tool returns (a one-time link) and covers the full lifecycle: how to use the link, how to confirm success via whoami, when to re-call, and the account-type limitation. An agent has everything needed to invoke it and verify the outcome.

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, but the description adds genuine meaning for the handle parameter by stating that 'typos in the handle are corrected to the authorized username.' This relaxes the exact-match requirement implied by the schema and tells the agent precision on the handle is not failure-critical.

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 first sentence states a specific verb and resource: 'Get a one-time link that connects an Instagram Business/Creator account to Pith so publish_post can post to it.' This both names the exact operation and ties it to its downstream consumer, and it is clearly distinguishable from all 30+ siblings, none of which handle account connection.

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 gives an explicit workflow ('Open the link in a browser, approve on Instagram, then call whoami to confirm'), a clear when-not ('personal accounts cannot use Instagram's publishing API'), and re-call guidance for expired links. It does not name an alternative tool for competing scenarios, but no sibling serves this function, so the routing to whoami and publish_post is sufficient context.

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