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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description goes well beyond that: it discloses truncation behavior, that availableSections/missingSections report coverage, that missing sections are reported rather than invented, and that unknown names return isError with suggestions instead of an automatic substitute. That is exactly the kind of error/edge-case disclosure annotations cannot carry.

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?

Four tight sentences, front-loaded with what the tool does, then input flexibility, then output/coverage semantics, then error behavior. Telegraphic style keeps it compact without padding, though a couple of clauses ('orientation meanings by default') require the schema to fully parse.

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 enumerated, and the description still usefully explains the coverage/truncation signals. It covers input aliasing, orientation filtering, and error behavior. The remaining gap is sibling routing and interaction with search_tarot_cards, which an agent still has to guess.

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 only 50%, and the description compensates substantially: the 'card' parameter is undocumented in the schema but the description tells the agent it accepts names, slugs, numeric names, and Coins aliases. It also clarifies that 'sections' takes exact normalized IDs and that 'brief' defaults to orientation meanings only. Good added meaning, though per-section boundaries remain schema-only.

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 opens with a specific verb+resource: 'Read authored meanings with source links,' which is precisely what the tool does. It does not name or contrast with the siblings (search_tarot_cards, get_tarot_spreads), so an agent must infer that this is the single-card detail lookup rather than a search. Clear purpose, but no explicit sibling differentiation.

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?

It gives concrete usage rules for the optional params: use 'brief' for bounded excerpts (orientation meanings by default) and 'sections' to select exact normalized section IDs. It also states the error path for unknown names. What is missing is any guidance on when to pick this tool over search_tarot_cards or get_tarot_spreads.

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