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Get certificate

get_certificate

Read-onlyIdempotent

Return the full record of one certificate: subject, issuer, serial number, validity, DNS names, key and signature details, the CT log entries that recorded it and download URLs for the certificate body. id is the id field of a search result or the certificate's SHA-256 fingerprint (64 hex characters).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "id": "<id>"
    },
    "name": "get_certificate"
  }
}

Input Schema

Name	Required	Description	Default
`id`	Yes	A search-result id or a 64-hex SHA-256 fingerprint

Output Schema

Name	Required	Description	Default
`id`	Yes
`is_ca`	Yes
`san_dns`	Yes
`san_more`	Yes
`sig_algo`	No
`downloads`	Yes
`issuer_ca`	No
`issuer_dn`	Yes
`not_after`	Yes
`not_before`	Yes
`serial_hex`	Yes
`subject_dn`	Yes
`log_entries`	Yes
`policy_oids`	Yes
`final_sha256`	No
`ext_key_usage`	Yes
`pubkey_sha256`	No
`precert_sha256`	No
`final_first_seen`	No
`log_entries_total`	Yes
`precert_first_seen`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 12, 2026

TDQS

A3.7/5.0

Behavior3/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is fully covered without the description. The description adds useful context on what the record contains, including CT log entries and download URLs, but since an output schema exists, this is mostly restatement rather than behavioral disclosure. No error or not-found behavior is described.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, front-loaded with the return contents and followed by the id contract; there is little filler. The enumerated field list mildly duplicates the output schema, but it reads as intentional orientation rather than bloat.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a one-parameter read tool with rich annotations and an output schema, the definition covers purpose, record contents and id format adequately. The only meaningful omission is failure behavior for an invalid or unknown id, which an agent would otherwise have to discover by calling.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% for the single id parameter, whose schema text ('A search-result id or a 64-hex SHA-256 fingerprint') already matches the description. The description expands it slightly by naming the id as the id field of a search result, but adds no format, validation, or edge-case detail beyond the schema, so baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Uses a specific verb ('Return the full record') on a specific resource ('one certificate') and enumerates the record contents: subject, issuer, serial number, validity, DNS names, key/signature details, CT log entries, download URLs. The singular 'one certificate' contrasts clearly with the sibling search_certificates, so an agent can tell lookup from search without opening either schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied by the phrase 'one certificate' and by the id format hint, which suggests a follow-up call after a search. There is no explicit when-to-use statement, no exclusion such as 'use search_certificates instead when you only have a domain', and no note on what happens when the id is unknown.

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

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