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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the safety profile is fully covered by structured data. The description adds one genuine behavioral fact beyond that — 'Available on every plan (no AI credit cost)' — which tells the agent this call is free even on metered plans. Beyond that single note it adds no other runtime context, so it is a moderate rather than rich contribution.

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?

Front-loaded with the return payload first, then availability/cost, then usage triggers. Dense and largely waste-free, though the final sentence is a long parenthetical chain of three pre-check examples that could be trimmed without losing meaning.

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 values need not be explained, yet the description still previews the key quota dimensions. Combined with zero params and full annotation coverage, nothing an agent needs to invoke this correctly 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?

The tool takes zero parameters, so the baseline is 4 and there is no syntax or format information the description needs to supply. The phrase 'the user's current' correctly conveys that the scope is implicit rather than parameterized.

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?

States a specific verb and resource (return current subscription tier and per-tier quotas) and enumerates the quota categories returned: channels, storage, AI credits, posting. That is clear enough for selection, though it never distinguishes itself from the sibling get_plan, which an agent could easily confuse it with.

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?

Explicitly says when to call (user asks about plan or limits) and when to call proactively, naming concrete trigger conditions and the exact sibling operations involved (create_post_draft with low aiCalls, schedule_post on FREE, connect_channel near the channel cap). This is the strongest possible routing guidance.

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