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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive/non-open-world behavior, so the safety profile is covered. The description adds what the annotations cannot: that results are paginated, that entries carry global_creator_id, and that this ID is the key the lookup tool consumes. It does not mention rate limits or total-count behavior, which keeps it short of a 5.

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 opening is front-loaded with the trigger condition, followed by capability, result shape, and next step in a logical order with no filler sentences. The quoted example queries are slightly redundant with the 'browse and filter' statement but they earn their place by anchoring to real user phrasing.

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?

With no output schema, the description must carry return-value information, and it does identify the key returned field (global_creator_id) and the pagination model. It stops short of describing the other fields in a result row (name, ISNI/IPI presence), which an agent composing a response would benefit from, but nothing needed to invoke the tool correctly is missing.

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 every parameter is already documented with its own description, and the description's filter list (q, ISNI, IPI, letter) mostly restates those fields. The one genuinely additive detail is spelling out that 'letter' accepts '#' for numeric entries, and that nuance also appears in the schema. Baseline 3 is correct here.

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 gives a specific verb and resource ('Browse and filter creators in the PICA public directory') and reinforces it with concrete user utterances such as 'people starting with B'. It also distinguishes itself from the sibling by naming directory_lookup_person as the drill-down step, so an agent can separate listing from lookup without reading either schema.

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 states explicitly when to use the tool via quoted trigger phrases, and it names the concrete follow-on ('→ then: directory_lookup_person') for the case where the agent needs identifiers, roles, or collaborators. That is when-to-use, when-to-continue, and alternative routing all in one short block.

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