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

The annotations already indicate this is read-only and non-destructive, and the description is consistent with that. However, the description adds no behavioral context beyond the purpose statement—no mention of pagination, limits, output shape, filtering behavior, or what happens when invoked with no parameters, so it fails to disclose anything beyond what annotations already convey.

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 a single short sentence with no wasted words, making it easy to scan and parse. It is appropriately concise, though it is so terse that some useful context is omitted, which keeps it from being a perfect 5.

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?

There is no output schema, so the description carries extra responsibility for clarifying what the tool returns and how parameters affect behavior. It only says 'Fetch fulfillment events for intents,' leaving unclear what a fulfillment event contains, how hashes map to results, whether hashes are required, and how the arbitrary 'params' object modifies the query. Given the large sibling set and ambiguous generic schema types, this is under-specified.

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%, so the schema already documents 'hashes' as 'Intent hashes' and provides a description for the raw JSON 'params' object. The description adds little beyond what the schema provides, which fits the baseline of 3; it neither clarifies param semantics further nor leaves them undocumented.

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 states a specific verb ('Fetch') and a clear resource ('fulfillment events for intents'), which makes the tool's core purpose identifiable. However, it does not differentiate this tool from similar siblings like peer_indexer_intents_fulfillment_amounts or peer_indexer_intents_fulfillment_and_payment, so it stops short of a 5.

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 implies the tool is for retrieving fulfillment events tied to intents, which gives basic usage context. It provides no explicit guidance about when to prefer this tool over the many closely related indexer/intent tools, nor any exclusions or alternative routing.

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