List subscriptions

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

With readOnlyHint/openWorldHint annotations already covering safety and dynamic data, the description adds meaningful behavior: hidden subscriptions are included for the logged-in user, results include URL and membership state, and refresh can bypass a 10-minute cache. No annotation contradiction; the annotations and prose are consistent.

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?

One tightly worded sentence states the scope, edge case (hidden subscriptions), and output shape without repeating the title or schema. It is front-loaded and every clause earns its place.

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 simple read-only list with fully documented optional parameters, the description covers the key return values and the main behavioral variants. It could mention the unspecified behavior when not logged in and no username is provided, but that is a minor edge case given the schema's explicit username note.

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 description coverage is 100%, so the schema already documents refresh and username thoroughly. The description indirectly clarifies the username semantics by contrasting public and logged-in lists, but it adds little beyond what the schema states, matching the baseline for full coverage.

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 names a specific verb ('List'), resource ('every newsletter the logged-in user subscribes to'), and includes the hidden-from-public-profile scope plus the fields returned. This clearly differentiates the private logged-in list from the public one accessed via username, and from unrelated siblings like get_feed or list_chats.

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 and username parameter make the main conditional explicit: when not logged in, use username to read a public list; when logged in, get the full private list. It does not explicitly name sibling alternatives or exclusion cases, but the tool's purpose is distinct enough that no competing sibling exists for listing subscriptions.

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