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

With no annotations, the description carries the full transparency burden. It adds useful context (durable, advance notices, filtering by recent calls, price vs quality separation). However, it under-specifies key requirements (whether at least one key is mandatory) and whether any side effects occur. This leaves gaps for the agent but provides some meaningful behavioral disclosure.

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, front-loaded with the action and key usage note. Every word earns its place; no redundancy or fluff. Ideal size for a simple read tool.

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 read-only tool with two optional parameters and no output schema, the description covers the core aspects: what it reads, scope (recently called capabilities), and how to authenticate (supply one of the keys). It lacks edge-case details (e.g., behavior when both keys are supplied) but is sufficiently complete for an agent to invoke correctly in most scenarios.

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 input schema already contains full descriptions for both api_key and agent_key, so baseline is 3. The description adds the 'or' relationship between the two parameters, which is helpful but minimal. It doesn't compensate for any missing parameter details beyond what the schema already provides.

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 uses a specific verb ('Read') and resource ('durable advance notices for capabilities this buyer called recently'), which clearly distinguishes it from siblings like capability_get or capabilities_list. The added phrase 'price remains separate from quality' further sharpens the tool's unique purpose.

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 clear context: this tool is for reading price-change notices for capabilities the buyer recently called. It also instructs to supply a key (agent_key or api_key). While it doesn't explicitly name alternatives or exclusions, the contextual specificity effectively guides the agent on when to use it.

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