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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, so the safety profile is covered. The description adds genuinely non-derivable behavior: the response is delivered as an SSE stream rather than one payload, crediting at 100 credits (Tier 4), and the concrete endpoint. It omits auth requirements and why idempotentHint=false, which keeps it out of 5 territory.

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?

Short and front-loaded: the core capability leads, with bracketed metadata (group, endpoint, required param, cost) following compactly. Every line carries information, though the template-style [Group:]/[Endpoint:] format is more machine header than prose.

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 streaming tool with no output schema and a nested chart parameter, the definition covers the essential facts (SSE transport, required message, optional chart, cost). It does not describe what the stream emits or how chart context influences the completion, leaving gaps an agent would notice mid-invocation.

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 60%, with the nested chart object heavily documented in the schema itself (timezone, houseSystem letters, lat/lon full names, ayanamsa). The description adds only 'optional chart context', which restates the schema's required list. Baseline 3 is appropriate when the schema does most of the work.

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+mechanism: 'Server-Sent Events streaming chat completion with optional chart context.' An agent can tell this is a streaming chat tool rather than a static computation. It does not explicitly name or contrast with the closest sibling astroway_mcp_ai_chat, so it stops short of a 5.

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 or when-not-to-use guidance. Nothing tells the agent to prefer this over astroway_mcp_ai_chat (non-streaming chat) or astroway_mcp_tool_call_stream; the streaming qualifier implies a context but the choice is left entirely to inference.

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