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

Annotations already declare readOnlyHint/idempotentHint/non-destructive, so the closing 'Read-only' is redundant. The description nonetheless adds material behavior beyond the annotations: absent days are omitted rather than zero (a critical semantics trap for an agent), and auth/tier limits are disclosed via the X-API-Key header and window_notice.

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?

Three tight sentences, front-loaded with the return shape, followed by the absent-vs-zero caveat and then the access rules. Nothing is padded and each clause carries distinct information.

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 an output schema present, the description need not document return fields, and it still covers the non-obvious gaps: observation density per point, missing-day semantics, free-tier window, and API-key authentication. An agent has everything needed to call it correctly and interpret results.

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 symbol, metric and days are already documented with examples and bounds. The description only reinforces the symbol/metric pairing via its example and touches the 7-day default indirectly through tier language; it adds little parameter meaning beyond the schema.

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?

States a specific verb and resource — 'Returns the daily series for one network metric' — and pins down grain (one point per UTC day) and an example invocation (symbol=AKT metric=GPU_ACTIVE). It is clearly separable from listing tools like get_network, though it never names a sibling explicitly to route against.

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?

Offers contextual guidance about windowing — the free tier serves 7 days and signals it via window_notice, and an X-API-Key header unlocks your tier's window — which tells the agent what to expect but not when to prefer this tool over alternatives such as get_stats or get_network. Usage is implied rather than stated with exclusions.

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