List Subscriptions

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint, so the safety profile is covered. The description adds genuinely new behavioral context: the quota cost model (1 unit per page of up to 50 results), which is essential for an agent budgeting API calls and explains why results are paginated in 50-item pages despite a limit maximum of 500. It does not describe pagination termination or the shape of the response, which keeps it from a 5.

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?

Two sentences, no filler, with the core purpose front-loaded and the quota note isolated as a second sentence. Every sentence earns its place and nothing is redundant with the title or schema.

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?

An output schema exists, so return-value documentation is correctly omitted, and the quota/paging note supplies the key operational fact the structured fields lack. For a simple zero-required-parameter read tool this is close to sufficient; only an explicit hint about using page_token to continue past the 50-result page boundary 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?

Schema description coverage is 100% and all four parameters (limit, order, my_channel, page_token) are documented in the schema, including defaults, enum values, and paging semantics, so the description need not repeat them. It adds only the implicit page-size unit (50 per page), which is tangential to parameter meaning. Baseline 3 is appropriate.

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 identifies the resource precisely (channels the authorized user is subscribed to), which lets an agent separate it from read-only list siblings like list_playlists and from the mutation siblings subscribe/unsubscribe. It is a noun fragment rather than a verb phrase, but the name and title already supply the 'list' verb, so the pairing is unambiguous. It does not explicitly differentiate itself from other 'list' siblings, keeping it below a 5.

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?

There is no statement of when to use this tool, when not to, or what alternative exists. An agent must infer from the name alone that this reads the authorized user's own subscriptions rather than another channel's subscribers. No prerequisites or context are given.

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