Reading plans

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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so the safety profile is covered. The description adds useful context beyond that: it discloses the shape of returned data (citation, PTS page, get_text arguments, English links) and notes it works offline. It does not mention limits such as the 400-day maximum or what happens if an unknown plan name is supplied.

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?

Three short sentences, front-loaded with the resource and its valid values, then the retrieval semantics, then the offline note. No filler. The plan-name list is duplicated from the schema, which is mildly redundant but useful as a front-loaded enumeration.

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?

A simple two-parameter read tool with full annotation coverage and no output schema; the description compensates for the missing output schema by naming the return fields, and covers the empty-parameter cases. Nothing an agent needs in order to call it correctly is absent.

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 100% and defines types and bounds, but the description adds meaning the schema cannot: the behavioral effect of omitting each optional parameter (empty name lists plans, empty day returns the full schedule). For a tool with zero required parameters, that is exactly the missing semantic layer.

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 resource (reading plans) with an enumerated set of plan names and a specific operation (retrieve that day's readings with citation, PTS page, get_text arguments, English links). An agent immediately knows what it gets back. It does not explicitly differentiate from the closest sibling, daily_text, but the day-of-a-named-plan framing is distinctive enough in practice.

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 covers all three invocation modes: name+day for a single day's readings, omit name to list plans, omit day for the whole schedule. This maps directly onto the optional-parameter structure and removes any guesswork about how to enumerate plans.

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