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

Annotations already declare readOnly/idempotent/openWorld=false, so the description's job is to add context, and it does: it discloses the verification-date model, daily automatic monitoring, the 180-day staleness rule, that the response reports the stale count, and the slug/siblings relationship. It stops short of pagination or auth details, but this is well above annotation coverage.

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 dense sentences, front-loaded with what the tool is, then the data model, then the filters. Semicolon-heavy clauses are compact rather than padded; nothing reads as filler.

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 usefully covers the return shape (slug, siblings, stale count) and the filtering model. Ordering, pagination behavior, and the limit default are left to the schema, which is a minor remaining gap.

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 75% (only 'category' lacks a description but carries an enum), so the schema already carries most parameter meaning. The description reiterates the filterable fields but adds little syntax or format detail beyond what the schema provides, matching the baseline for high coverage.

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 precise verb+resource ('Search the human-verified directory of merchants that accept native Bitcoin') and scopes it to on-chain + Lightning everyday goods. This is unmistakable against the sibling tools, which are all price/gauge/treasury data lookups rather than directory searches.

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?

Explicitly names the three filtering axes (free-text query, category, country) and explains what the directory contains, so the agent knows when this tool applies. There are no competing search siblings to exclude, so the absence of a 'use X instead' clause is not a real gap.

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