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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. Beyond that, the description usefully discloses that results are relevance-ranked ('Best matches first') and that matching is semantic as well as literal, which an agent would not infer from the schema alone. It doesn't mention the result cap (limit max 50) or output shape, but the added ranking behavior is real value over 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?

A single tight sentence listing the match dimensions plus a short ordering clause – every element earns its place. The most important information (what you can search by) is front-loaded, and the parenthetical examples are compact rather than decorative.

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 6-parameter search tool with no output schema, the description covers the search surface and result ordering well. It stops short of describing the return shape (e.g. characters with codepoints/names) or how multiple filters compose, which leaves a modest gap given there is no output schema to fall back on.

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 83%, so the baseline is 3. The description earns above baseline because it expands the query semantics beyond the schema's 'name, description, codepoint, or character' to include aliases, keywords, and meaning, with worked examples that clarify the fuzzy matching behavior. The filter parameters are left to the schema, which documents them adequately.

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+resource (find Unicode characters) and enumerates the match dimensions: name, alias, keyword, codepoint, the character itself, and meaning. The concrete examples ('tick' finds ✓, 'return key' finds ⏎) make the fuzzy-match behavior unmistakable. It never names the sibling get_character or explains how it differs from a direct lookup, so it falls short of full sibling differentiation.

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?

Usage is only implied by the verb 'find' – an agent can infer this is the discovery tool and get_character is the direct lookup, but nothing states when to prefer one over the other. There is also no guidance on how the filter parameters (block, script, category, emoji) combine or interact with the query. Adequate but with clear gaps.

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