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

With no annotations, the description carries the full burden and does disclose the two costly prerequisites (EIP-191 signature and SHA-256 proof of work) plus the referral binding of inviter_code. It omits whether registration is idempotent or permanent, whether it costs gas, what a failed PoW or expired signature does, and what the call returns.

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?

Two sentences, no filler, with the mechanism stated first and the prerequisite/optional parameter second. The only weakness is that the opening sentence describes the effect as 'Register' rather than anchoring the tool's identity as invitation generation.

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 7-parameter, 5-required mutation with no annotations, no output schema, and 14% schema coverage, the description is thin. It should explain where nonce and chain_id come from, what the call produces, and what failure modes (expiry within 300 seconds, PoW rejection) look like.

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 only 14%, and the description clarifies the meaning of signature (EIP-191), pow_counter (SHA-256 work), and inviter_code (optional referral). It leaves nonce, wallet_address, and chain_id (default 8453) unexplained — notably it never says the nonce comes from the registration protocol call, which is the most likely source of invocation errors.

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 says 'Register with one EIP-191 signature and SHA-256 proof of work', which names a concrete mechanism, but the tool is named generate_a2a_invitation and the description never mentions generating or returning an invitation. An agent cannot tell whether this registers an identity, mints an invitation token, or both.

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?

It explicitly routes the agent to get_a2a_registration_protocol for the canonical message and current difficulty, which is a genuine prerequisite for producing a valid signature and PoW. It stops short of stating when not to use it or what happens if the protocol tool was not called first.

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