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

Annotations already declare readOnly/idempotent/non-destructive, and the description still adds substantial behavioral context: retention-window semantics with page.retention_hours / page.retained_since, what an empty page means, scope-gated failure mode, and exact pagination contract. This is well beyond what the structured fields 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?

Dense but front-loaded: purpose and field list come first, then usage, then the pagination and retention mechanics. Every sentence carries operational information and none is filler, though the pagination sentence is long enough to slow scanning.

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 compensates by naming the returned fields, the page envelope fields, and edge cases (empty page, retention window). An agent has everything needed to invoke and paginate correctly.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning: it explains cursor round-tripping (page.next_before/page.next_before_id back as before/before_id), that all_projects must stay constant across pages, and that only_errors means anything other than 'success'. Only minor gaps remain (e.g., it doesn't restate limit/status semantics).

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 opens with a precise verb+resource+ordering ('Recent API calls in your key's project, newest first') and enumerates the returned fields, so the agent knows exactly what it gets. It also distinguishes itself from spicrawl_usage for billing totals, separating it from the nearest ambiguous sibling.

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?

Explicit when-to-use cases are given ('find failing calls (only_errors=true) or spot patterns across a target'), plus the alternative all_projects=true mode with its precondition (needs `read` scope, else 403 ERR::AUTH::INSUFFICIENT_SCOPE). It even routes to a sibling ('Not billing-grade: use spicrawl_usage for totals').

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