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 adds two things beyond them: the exact-then-substring matching strategy, which affects how loosely a keyword can be specified, and a cost caveat that billing for this endpoint is not in the public credit manifest. It does not mention result-count limits or truncation behavior.

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?

Two tight sentences with the core action front-loaded, followed by bracketed group/cost metadata. Every line carries information; the cost caveat is worth its space, though the group tag is boilerplate.

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-value explanation is unnecessary, and annotations carry the safety profile. Combined with full schema coverage and the matching-behavior note, the definition is adequate; only sibling routing 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?

Schema description coverage is 100%, so all three parameters (keyword, fields, precision) are already documented in the schema, including the compact-mode semantics. The description adds nothing about `fields` or `precision`, so baseline 3 is correct.

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+resource ('Look up a dream symbol by keyword') and adds the lookup mode (exact match, falling back to partial substring). It is distinguishable from astroway_esoteric_dreams_decode and astroway_esoteric_dreams_recurring_themes by being a single-symbol keyword lookup, but it never names or contrasts those siblings explicitly.

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, when-not-to-use, or alternative-routing guidance. With four dream-domain siblings (dreams, dreams_decode, dreams_by_element, dreams_recurring_themes) an agent gets no help deciding between a symbol lookup and a full dream decode.

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