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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial context beyond them: word-based matching that ignores accents and case, a 60 calls/minute per IP rate limit, no authentication, and an at-most-daily data refresh. These are exactly the operational traits an agent needs and none are derivable from the annotations.

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?

Front-loads purpose and the call-this-first directive, then layers coverage, matching behavior, return shape and limits. Every sentence earns its place; nothing is padding despite the density.

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 single-parameter discovery tool with an output schema, the description is complete: it explains coverage scope, matching rules, result cardinality and fields, error semantics, rate limits and freshness. An agent has everything needed to invoke and interpret it 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 query parameter is already documented, but the description adds real meaning: matching is every-word, accent- and case-insensitive, series names are Spanish so Spanish keywords work best, with concrete examples ('inflacion', 'dolar', 'reservas'). This goes beyond the schema's single example and helps the agent formulate a better query.

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 ('Find Argentine economic time series by keywords and get their keys') and explicitly positions itself relative to siblings get_series and get_projection. An agent can distinguish this discovery tool from the history/forecast tools without opening a 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?

Gives explicit when-to-use guidance ('Call this first whenever you don't already know a series key') and names the downstream alternatives with their purpose. It also covers the negative case: an empty list means no match, not an error, so the agent knows not to retry or treat it as failure.

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