get_agent_signup_info

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered structurally. The description adds genuinely new context: this is an instructional tool and it covers 'safe human-in-the-browser boundaries', which tells the agent a human must act in a browser at some steps. It does not say what form the explanation comes back in (text vs. structured steps), a minor gap for a no-output-schema tool.

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 sentence, front-loaded with the verb and purpose, with the only additional clause ('including the safe human-in-the-browser boundaries') earning its place by flagging the human-interaction constraint.

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 zero-parameter, read-only informational tool with no output schema, the description says enough to call it correctly and to know why. What remains missing is the expected return shape and the handoff to the actual signup/API-key tools, which would help an agent chain the workflow.

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?

The tool takes zero parameters and the schema is empty, so there is no parameter meaning for the description to supply. Baseline 4 applies.

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 ('Explain') and resource (agent-led signup workflow via posterly MCP before an API key exists), which clearly separates it from action siblings like start_signup, get_signup_session or create_api_key. It stops short of naming those siblings, so differentiation is implied rather than explicit.

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 phrase 'before an API key exists' gives a concrete precondition that tells the agent when this tool applies rather than the signup/API-key tools. It does not name the follow-up tools (start_signup, create_api_key) an agent should call afterwards, so the routing guidance is incomplete but still clear.

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