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

Annotations already cover the safety profile (readOnly, non-destructive, open-world, non-idempotent). The description adds two genuinely useful behavioral facts beyond them: the response arrives as Server-Sent Events, and each call costs 100 credits (Tier 4). It says nothing about auth requirements, rate limits, or what the stream events look like, so it is adequate but not rich.

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?

One front-loaded sentence that states the core capability, followed by two bracketed metadata tags. Very tight, though the group/cost tags sit after the payload rather than being folded in naturally.

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 5-parameter tool with a nested birth-chart object, no output schema, and only 60% schema description coverage, the definition is thin. It does not describe the streamed response shape, streaming lifecycle, or the required message parameter, and gives no guidance on how chart context should be formed.

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 60% and the nested chart object carries extensive inline documentation that the description does not repeat. The 'optional chart context' phrase confirms the chart parameter exists but adds no semantics for message, language, fields, or precision, so it does not compensate for the coverage gap.

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 and resource: an SSE streaming chat completion, with the chart-context option noted. It is clearer than a bare 'chat', but it never distinguishes itself from sibling astroway_mcp_ai_chat (presumably the non-streaming counterpart) or astroway_mcp_tool_call_stream, so the agent must guess which chat entry point to pick.

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?

No when-to-use, when-not-to-use, or alternative guidance is given. The description notes that chart context is optional but never says when you should supply it or how it changes the answer, and it never mentions the sibling chat tools as alternatives.

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