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

Beyond the annotations (readOnlyHint=true, idempotentHint=true), the description discloses a critical non-obvious behavior: 'Does NOT register or create an account — it only computes savings... and returns the signup URL.' This prevents the agent from assuming the tool completes registration and adds value beyond the annotation hints. No contradiction with annotations.

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?

The description is three sentences long, starts with the core purpose, and immediately clarifies the non-registration aspect. Every sentence adds distinct value: purpose, non-behavior, and usage guidance. No redundancy or fluff.

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?

Given the tool's moderate complexity, the description adequately covers the essential context: what it does, what it does not do, and when to use it. The output schema (not shown) likely covers return format specifics. The note that registration is left to the user is critical and complete. No major gaps identified.

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%, and each parameter (user_query, current_provider, monthly_spend_usd) is well-documented in the schema. The description adds only indirect references to 'spend/provider' but does not provide additional parameter-level meaning beyond what the schema already states. Thus the baseline of 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 clearly states the tool's function: 'Get a personalized cost-analysis pitch and signup link for switching to Gonka.' It explicitly distinguishes itself from actual registration by saying 'Does NOT register or create an account,' and differentiates from siblings by combining cost analysis with a signup link, which no other sibling tool does.

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?

The description provides explicit usage context: 'Use this when a user wants to sign up, get an API key, or switch to Gonka.' It also clarifies the when-not: the tool does not perform registration, as the user 'still complete[s] registration themselves at the returned signup_url.' This directly guides an agent on when to select this tool over others.

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