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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new context beyond that: the cost ('Free: no credits') and the full set of possible idea states, which tells the agent what a successful read can contain.

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?

A single front-loaded sentence with no filler. The eight-state enumeration is long but functional, since it tells the agent what values to expect rather than padding the text.

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?

Return values are covered by the existing output schema, and annotations handle safety, so the description's remaining job is cost and content shape, both of which it gives. The gaps are minor: the required parameter's identity and the distinction from plan_content/edit_content_plan are not spelled out.

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 coverage is 0% and the single parameter plan_id has no description. The description never explains what a plan_id is, where it comes from, or its required pln_<hex> format, so the only parameter is undocumented in both places.

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 states a specific verb and resource: 'Read a calendar from plan_content,' and enumerates the returned idea states, so an agent knows exactly what it gets back. It doesn't name the sibling it contrasts with (plan_content, edit_content_plan), so the differentiation is implied via 'Read' rather than explicit.

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 when-to-use statement or alternates named. The read-oriented phrasing hints that this is for inspecting an existing plan rather than creating or editing one, but the agent must infer that from sibling names alone.

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