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

Beyond the annotations, the description adds valuable behavioral context: it is an 'additive external write' (clarifies the side effect), it explicitly says 'do not fetch or open the destination' (prevents accidental network calls), and it explains guest-flow behavior when no auth is supplied. The idempotency-key guidance also goes beyond the schema annotations. No contradictions with readOnlyHint=false, destructiveHint=false.

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, front-loaded with the primary action, followed by usage trigger, safety note, auth caveat, and retry guidance. Every sentence earns its place; no fluff or repetition.

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 has 8 parameters, full schema descriptions, an output schema, and annotations, the description adds the missing behavioral and usage context: it clarifies the external write nature, guest-flow, and not to fetch the destination. It also points to idempotency handling. This is complete for the tool's complexity.

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 input schema already provides 100% descriptive coverage for all 8 parameters, so the baseline is 3. The description mentions the idempotency key and HTTP/HTTPS url, but these are already covered in the schema. The description does not add new parameter-level semantics beyond what the schema provides, so no score above baseline.

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 opens with a specific verb+resource: 'Create a MiniURL short link for a supplied HTTP or HTTPS destination.' It clearly distinguishes from siblings by focusing on single-URL shortening, rather than bulk operations like bulk_create_links or alias checks like check_alias. The second sentence reinforces the exact trigger condition.

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 'Use when' condition: 'when the user asks to shorten a URL or generate a MiniURL link.' It also provides contextual warnings about not fetching the destination and the guest-flow fallback when authentication is missing. It stops short of naming alternative tools for exclusions, so it earns a 4 not a 5.

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