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), so the bar is lower. The description adds genuinely new operational context not in structured fields: the POST endpoint and the 10-credit Tier 1 cost, which matters for an agent deciding whether to call it.

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?

Purpose is front-loaded in the first sentence, followed by a compact bracketed metadata block (group, endpoint, required, cost) with zero filler. Slightly terse on the behavioral sentence, but nothing is wasted.

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 single-text-input tool with an output schema present, the description needn't explain return values, and the cost/input-requirement disclosure covers the practical needs. The only real gap is not distinguishing this decoder from the sibling symbol-keyword lookup.

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 50%: 'fields' and 'precision' carry their own descriptions, while 'text' and 'recurring' do not. The description partially compensates by flagging 'text' as required and gesturing at the recurring/single-event distinction, but never explains what the recurring toggle actually changes. Baseline 3 is appropriate.

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: 'Scan dream narrative text for known symbols,' then states the output shape (matched symbols with meanings). This clearly separates it from keyword-lookup siblings, though it never names an alternative like astroway_esoteric_dreams_symbol_keyword 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 or when-not-to-use guidance and no alternative named, despite several close siblings (dreams_symbol_keyword, dreams_recurring_themes, dreams_by_element). The parenthetical '(recurring or single-event)' hints at a mode but does not tell the agent which one applies to a given request.

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