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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is fully covered structurally. The description adds modest value by indicating the result is presented 'line by line,' hinting at the return shape. It says nothing about date-default behavior beyond what the schema states (defaults to today UTC).

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?

The first sentence is front-loaded and precise, but the second is app-level marketing boilerplate ('plans, search, and the whole Meditations, Enchiridion and Seneca's letters read a passage at a time') that describes features belonging to other sibling tools, not this one. Nearly half the description does not earn its place for a single-parameter daily-reading tool.

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, idempotent tool with one optional parameter and no output schema, the description adequately conveys what is returned (today's Stoic passage, line by line) and the annotations cover safety. The only gap is the absence of any tie-breaking guidance against sibling reading tools, which is minor at this complexity.

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 the single date parameter is fully documented in the schema ('Optional day as YYYY-MM-DD. Defaults to today (UTC).'). The description adds no syntax, format, or boundary detail beyond that, so the baseline of 3 applies.

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 opening states a specific verb+resource combination: 'Today's reading, line by line (same as the app shows today),' which tells the agent this returns the current day's Stoic passage. It is distinguishable from siblings like stoics_get_reading and stoics_read_book by the 'today' anchor, though the tool never names those alternatives explicitly. The trailing sentence dilutes focus by describing app-wide features rather than this tool.

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 explicit when-to-use guidance or routing to alternatives. The phrase 'same as the app shows today' hints at the daily-reading use case but does not say when to prefer this over stoics_get_reading or stoics_read_book. An agent must infer the distinction from the name alone.

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