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

The read-only/no-side-effects statement largely duplicates the readOnlyHint and destructiveHint=false annotations, earning no extra credit. What the description does add is non-redundant: the exact cardinality (23 packages) and the full return shape, which matters because no output schema exists. It stops short of describing ordering or whether the list can change over time, so it is strong but not exhaustive.

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?

It is front-loaded with purpose, then usage, then the exclusion rule, then behavior and return shape. Every sentence carries distinct information; the return-shape sentence earns its place precisely because no output schema is defined.

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 parameterless, read-only listing tool with no output schema, the description supplies everything an agent needs: the payload contents, exact count, safety profile, return keys, and the routing rule to the sibling contract tool. Nothing material is missing.

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?

With zero parameters the baseline is 4, and the description confirms this explicitly ('No parameters: accepts empty input'), removing any doubt about whether input is required. There is no further parameter meaning to add.

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 and resource ('List the 23 published Designesy packages') and immediately enumerates the payload fields (versions, URLs, statuses). It also explicitly contrasts itself with the sibling designesy_contract, so an agent can distinguish the discovery tool from the detail-fetch tool without opening either 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 explicit when-to-use ('discover what Designesy publishes before fetching a specific contract') and an explicit when-NOT-to-use ('if you already know which package you need, skip this and call designesy_contract directly'). The alternative is named, not merely implied.

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