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

Annotations already declare readOnlyIdempotent non-destructive closed-world behavior, and the description adds substantial value beyond them: the conditional needs_setup return when no choices are saved, the fact that use_defaults scopes to this plan only, the authenticated-namespace requirement, and an explicit list of side effects it will not perform. The API-key handling warning is an extra operational safety note the annotations cannot express.

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 opening clause, and each subsequent sentence adds a distinct fact (contents, trigger, fallback state, exclusions, security note) with no filler. It is slightly dense at five sentences, but nothing reads as padding.

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?

With an output schema present, the description needn't describe return values, yet it still summarizes plan contents and the needs_setup fallback. Combined with full schema coverage and rich annotations, an agent has everything needed to decide when to call it, what to pass, and what to expect.

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 100%, so the baseline is 3, but the description adds real meaning: 'stack' is tied to selecting the reference implementation, and 'use_defaults' is constrained to applying defaults 'to this plan only when the user chooses them,' which sharpens the schema's softer 'set only when the user chooses to continue with defaults.' The reason/user_intent/namespace_id parameters get no additional description text, keeping this below a 5.

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: it 'returns an instrumentation plan for an MCP server in the authenticated Flowlines namespace,' and enumerates the plan's contents (span contract, field definitions, test cases, verification info, reference implementation). The scope is clear, but it never names or contrasts itself with closely related siblings such as check_onboarding, get_mcp_overview, or get_mcp_recommendation, so the agent must infer the boundary.

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?

Gives a clear triggering condition ('Use when the user requests help instrumenting their MCP server') and a strong negative boundary list (does not edit source code, change namespace settings, create API keys, deploy, or send test calls). It also explains the needs_setup branch and when use_defaults applies. It stops short of naming an alternative sibling to use instead, which keeps it from a 5.

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